By contrast, Pennsylvania state officials have made it a priority to ensure the state's dozens of financially troubled cities pay their bond investors first, so governments can keep borrowing, even if they have to shut schools, lay off firefighters and sell public utilities to make ends meet.
Pennsylvania law bars the city from filing for bankruptcy until at least 2023, noted Sam Katz, head of the state financial board that oversees Philadelphia's budget.
Plus, Detroit is in worse shape than Philadelphia.
"The real problem in Detroit is they have nothing going," said Alan Schankel, managing director at Janney Capital Markets' municipal bond unit. "You go there and it's very depressing. They have no engines like the University of Pennsylvania or the big medical institutions to contribute to the city's vitality."
Detroit in its heyday had close to two million residents, almost as many as Philadelphia at its peak. But the Motor City rose and fell with one industry - automobiles. It lost more than 60 percent of its population as factories shut and it failed to attract new employers. Homes and businesses were abandoned, property values stalled, tax collections fell, city services declined.
Detroit residents are more than twice as likely to be murdered as Philadelphians.
Philadelphia has also lost factories, stores and corporate headquarters, and many neighborhoods are scarred with abandoned plants and rowhouses. But it has regrouped as a center for universities, hospitals, tourism and professional services, with a core of busy office towers.
Median home values have more than doubled since 2000 in Philadelphia and are more than double the Detroit median, which barely budged.
Philadelphia households earn, on average, more than 40 percent more than Detroiters. About 29 percent of Philadelphians work at universities, colleges or schools; just 7 percent in Detroit. About 11 percent of Philadelphians hold "professional and technical" jobs; just 3 percent of the workforce in Detroit.
Philadelphia's population, though reduced almost a quarter from its early-1900s peak, rose slightly over the last decade, as more people moved into neighborhoods around Center City. Philadelphia attracts more college graduates and more immigrants than Detroit.
Yet Philadelphia suffers from many of the same challenges that Michigan officials used to justify forcing Detroit into the biggest municipal reorganization proposal ever filed under Chapter 9 of the federal bankruptcy code.
Both cities are still paying old debt from pro sports stadiums and other trophy projects that were supposed to attract jobs. And both now have more retirees collecting benefits than active workers paying into their pension systems.
Democratic politicians in both Philadelphia and Detroit have had a tough time getting Republican-led state governments to boost spending on services to the poor. Both cities charge higher taxes than nearby suburbs, making them less attractive to employers.
Greater wealth doesn't guarantee better financial health. Indeed, Chicago, which is wealthier than Philadelphia, with higher home values, higher median incomes, a higher proportion of college graduates and immigrants, and a lower murder rate, had its bond rating cut a frightening three steps, to A3, by Moody's Investors Service on July 17, the same day Detroit filed for bankruptcy.
Moody's rates Philadelphia A2, a step higher than Chicago. The higher the bond rating, the more likely credit analysts think a borrower will pay what it owes - and reduces the interest a borrower has to pay investors.
Moody's reports on the two cities show that analysts trust earnest-mannered Philadelphia Mayor Nutter, and Pennsylvania Gov. Corbett's oversight of city finances, more than Chicago Mayor Rahm Emanuel, potty-mouthed ex-chief of staff to President Obama, or Emanuel's likely support from Illinois' state government.
"Illinois has become the poster child of poor state credit. It has the weakest credit among the 50 states," said David Kotok, chairman of Vineland- and Sarasota, Fla.-based Cumberland Advisors. "Pennsylvania looks a lot better than Illinois."
Help from Harrisburg
"Philadelphia went through severe financial problems in the 1990s. They got state oversight and management. In Detroit, the state has done nothing like that," said Schankel, of Janneys.
In a report June 12, Moody's noted that Philadelphia will eventually have to pay out $5 billion more than it has set aside to pay pensions for its retirees, or perhaps as much as $8.5 billion, using more conservative investment assumptions. That gap is "well above average" for the size of the city, Moody's analyst Michael D'Arcy wrote.
But in downgrading Chicago, Moody's said that city's pension shortfall tops $19 billion, or $36 billion, using more conservative assumptions. While Chicago is almost twice as large as Philadelphia, its per capita pension shortfall is roughly four times as large.
Detroit's pension gap is manageable, according to data published by city pension actuary Gabriel, Roeder and Smith Co., of Southfield, Mich. But the state receiver, using far more cautious investment assumptions in a separate analysis by Milliman Inc., of Seattle, projects billions in unfunded liabilities, and used that to justify the bankruptcy filing.
Philadelphia had hoped to sell nearly $400 million in new and refinanced general-obligation bonds in June. But Federal Reserve chairman Ben Bernanke spooked bond investors by threatening to slow the Fed's massive purchases of government debt. New municipal bond issues, which had been pricing at roughly the same near-record low rates as U.S. Treasuries, suddenly rose to higher levels.
So Philadelphia postponed its borrowing until July, and rates started to slip back down. But then Detroit surprised investors by declaring bankruptcy, boosting bond rates almost as high as June's peak. On Thursday, Philadelphia sold $208 million in general obligation bonds, but city finance chief Rob DuBow said the rest of the issue - refunding existing bonds - would be postponed again.
"Bankruptcy is the ultimate failure of a municipal government," Fabian warned clients in a note last week.
But some observers say more cities should follow Detroit into bankruptcy.
"I like bankruptcy because it forces a municipality back to the basics: What happened, what do you do about it - and how do you pay for it?" said Main Line lawyer Mark Schwartz, who represented Harrisburg's City Council in its failed attempt to declare bankruptcy in the face of state resistance in 2012.
"The day Detroit filed Chapter 9, Central Falls, Rhode Island [which filed for bankruptcy in 2011] got its rating upgraded," Schwartz said. "What does that tell you? That the process absolutely works."
Contact Joseph N. DiStefano at 215-854-5194, JoeD@phillynews.com, or @PhillyJoeD on Twitter.