Detroit has become the largest U.S. city to file for bankruptcy, as it struggles with as much as $20 billion in debt. "This is a difficult step but the only viable option to address a problem that has been six decades in the making," said Michigan Gov. Rick Snyder. The filing opens the door for precedent-setting decisions on issues relating to bondholder repayment and the treatment of public pension obligations in municipal bankruptcies. The filing ended Detroit's efforts to reach an out-of-court settlement in the face of union opposition and a long list of creditors.