DETROIT — Detroit presented its first full road map for climbing out of bankruptcy Friday, outlining an elaborate plan to restructure $18 billion in debt, demolish thousands of blighted homes and invest in the broken-down infrastructure that has made the city a symbol of urban decay.

If approved by a judge, the sweeping proposal would mean sharply reduced payments to some retirees and creditors.

Pension holders could expect to get 70 percent to 90 percent of what they are owed, while many banks would receive as little as 20 percent.

The plan, which is sure to be the subject of court challenges, envisions a leaner, cleaner and safer Motor City after financial burdens are lifted.

Gov. Rick Snyder called the plan “a critical step forward.” But it leaves unanswered many questions, including whether creditors and labor unions will accept the deal or fight it, and how long that process might take.

The package calls for awarding police and fire retirees at least 90 percent of their pension after eliminating cost-of-living allowances. Other retirees would receive at least 70 percent.

Detroit’s woes began in the late 1960s, as auto companies began opening plants in other cities. Property values and tax revenue fell, and police couldn’t control crime. In later years, the rise of autos imported from Japan started to cut the size of the U.S. auto industry.