Supplemental Guarantor Condensed Consolidating Financial Statements Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net cash provided by (used in) operating activities	$ 377.6	$ 318.4	$ 223.0
Investing activities
Purchases of property, plant and equipment	(193.5)	(206.5)	(251.9)
Proceeds from sale of property, plant and equipment	0.3	9.1	9.1
Proceeds from government grants	5.1	2.1	0.0
Intercompany activity	0.0	0.0	0.0
Proceeds from sale-leaseback of equipment	0.0	0.0	24.1
Net cash used in investing activities	(188.1)	(195.3)	(218.7)
Financing activities
Net debt activity	(140.2)	(22.0)	104.8
Debt issuance costs	0.0	(0.3)	(16.7)
Employee stock option exercises, including tax benefit	0.8	1.2	1.1
Purchase of treasury stock	(3.1)	(0.3)	(0.4)
Payments to Noncontrolling Interests	1.1	0.0	0.0
Intercompany Activity - Financing	0.0	0.0	0.0
Net cash provided by (used in) financing activities	(143.6)	(21.4)	88.8
Effect of exchange rate changes on cash	(12.6)	(6.5)	(1.5)
Net increase in cash and cash equivalents	33.3	95.2	91.6
Cash and cash equivalents at beginning of year	249.2	154.0	62.4
Cash and cash equivalents at end of year	282.5	249.2	154.0
Holdings [Member]
Net cash provided by (used in) operating activities	0.0	0.0	0.0
Investing activities
Purchases of property, plant and equipment	0.0	0.0	0.0
Proceeds from sale of property, plant and equipment	0.0	0.0	0.0
Proceeds from government grants	0.0	0.0
Intercompany activity	0.0	0.0	0.0
Proceeds from sale-leaseback of equipment			0.0
Net cash used in investing activities	0.0	0.0	0.0
Financing activities
Net debt activity	0.0	0.0	0.0
Debt issuance costs		0.0	0.0
Employee stock option exercises, including tax benefit	0.0	0.0	0.0
Purchase of treasury stock	(3.1)	(0.3)	(0.4)
Payments to Noncontrolling Interests	0.0
Intercompany Activity - Financing	3.1	0.3	0.4
Net cash provided by (used in) financing activities	0.0	0.0	0.0
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at beginning of year	0.0	0.0	0.0
Cash and cash equivalents at end of year	0.0	0.0	0.0
AAM Inc. [Member]
Net cash provided by (used in) operating activities	163.7	83.4	(35.9)
Investing activities
Purchases of property, plant and equipment	(36.4)	(51.3)	(61.2)
Proceeds from sale of property, plant and equipment	0.1	7.9	5.1
Proceeds from government grants	0.0	0.0
Intercompany activity	0.0	0.0	0.0
Proceeds from sale-leaseback of equipment			24.1
Net cash used in investing activities	(36.3)	(43.4)	(32.0)
Financing activities
Net debt activity	(142.8)	(7.8)	110.1
Debt issuance costs		(0.3)	(16.6)
Employee stock option exercises, including tax benefit	0.8	1.2	1.1
Purchase of treasury stock	0.0	0.0	0.0
Payments to Noncontrolling Interests	0.0
Intercompany Activity - Financing	(3.1)	(0.3)	(0.4)
Net cash provided by (used in) financing activities	(145.1)	(7.2)	94.2
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	(17.7)	32.8	26.3
Cash and cash equivalents at beginning of year	69.7	36.9	10.6
Cash and cash equivalents at end of year	52.0	69.7	36.9
Guarantor Subsidiaries of Certain Notes [Member]
Net cash provided by (used in) operating activities	68.1	41.9	64.9
Investing activities
Purchases of property, plant and equipment	(12.8)	(18.6)	(12.5)
Proceeds from sale of property, plant and equipment	0.1	0.4	0.5
Proceeds from government grants	0.0	0.0
Intercompany activity	55.0	23.3	52.6
Proceeds from sale-leaseback of equipment			0.0
Net cash used in investing activities	(67.7)	(41.5)	(64.6)
Financing activities
Net debt activity	(0.4)	(0.4)	(0.3)
Debt issuance costs		0.0	0.0
Employee stock option exercises, including tax benefit	0.0	0.0	0.0
Purchase of treasury stock	0.0	0.0	0.0
Payments to Noncontrolling Interests	0.0
Intercompany Activity - Financing	0.0	0.0	0.0
Net cash provided by (used in) financing activities	(0.4)	(0.4)	(0.3)
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at beginning of year	0.0	0.0	0.0
Cash and cash equivalents at end of year	0.0	0.0	0.0
Non-Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	145.8	193.1	194.0
Investing activities
Purchases of property, plant and equipment	(144.3)	(136.6)	(178.2)
Proceeds from sale of property, plant and equipment	0.1	0.8	3.5
Proceeds from government grants	5.1	2.1
Intercompany activity	0.0	0.0	0.0
Proceeds from sale-leaseback of equipment			0.0
Net cash used in investing activities	(139.1)	(133.7)	(174.7)
Financing activities
Net debt activity	3.0	(13.8)	(5.0)
Debt issuance costs		0.0	(0.1)
Employee stock option exercises, including tax benefit	0.0	0.0	0.0
Purchase of treasury stock	0.0	0.0	0.0
Payments to Noncontrolling Interests	1.1
Intercompany Activity - Financing	55.0	23.3	52.6
Net cash provided by (used in) financing activities	56.9	9.5	47.5
Effect of exchange rate changes on cash	(12.6)	(6.5)	(1.5)
Net increase in cash and cash equivalents	51.0	62.4	65.3
Cash and cash equivalents at beginning of year	179.5	117.1	51.8
Cash and cash equivalents at end of year	230.5	179.5	117.1
Consolidation, Eliminations [Member]
Net cash provided by (used in) operating activities	0.0	0.0	0.0
Investing activities
Purchases of property, plant and equipment	0.0	0.0	0.0
Proceeds from sale of property, plant and equipment	0.0	0.0	0.0
Proceeds from government grants	0.0	0.0
Intercompany activity	(55.0)	(23.3)	(52.6)
Proceeds from sale-leaseback of equipment			0.0
Net cash used in investing activities	55.0	23.3	52.6
Financing activities
Net debt activity	0.0	0.0	0.0
Debt issuance costs		0.0	0.0
Employee stock option exercises, including tax benefit	0.0	0.0	0.0
Purchase of treasury stock	0.0	0.0	0.0
Payments to Noncontrolling Interests	0.0
Intercompany Activity - Financing	(55.0)	(23.3)	(52.6)
Net cash provided by (used in) financing activities	(55.0)	(23.3)	(52.6)
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at beginning of year	0.0	0.0	0.0
Cash and cash equivalents at end of year	$ 0.0	$ 0.0	$ 0.0