Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income	$ 94.5	$ 366.7	$ 137.1
Other comprehensive income (loss), net of tax [Abstract]
Defined benefit plans, net of $(41.3) million and $32.3 million of tax in 2013 and 2012, respectively	76.6	(58.9)	(63.5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax	(26.2)	(9.4)	(27.3)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	(2.0)	7.8	(6.8)
Foreign currency translation adjustments	(26.2)
Other comprehensive income (loss)	48.4	(60.5)	(97.6)
Comprehensive Income	142.9	306.2	39.5
Net loss attributable to noncontrolling interests	0	1.0	5.7
Foreign currency translation adjustments attributable to noncontrolling interests	0	0.3	0.2
Comprehensive income attributable to AAM	$ 142.9	$ 306.9	$ 45.0