Supplemental Guarantor Condensed Consolidating Financial Statements Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net cash provided by (used in) operating activities	$ 407.6	$ 377.6	$ 318.4
Investing activities
Purchases of property, plant and equipment	(223.0)	(193.5)	(206.5)
Proceeds from sale of property, plant and equipment	1.7	0.3	9.1
Purchase buyouts of leased equipment	(4.6)	0.0	0.0
Proceeds from government grants	2.8	5.1	2.1
Final distribution of Reserve Yield Plus Fund	1.0	0.0	0.0
Acquisition of business, net	(5.6)	0.0	0.0
Intercompany activity		0.0	0.0
Net cash used in investing activities	(227.7)	(188.1)	(195.3)
Financing activities
Net debt activity	23.3	(140.2)	(22.0)
Debt issuance costs	0.0	0.0	(0.3)
Employee stock option exercises, including tax benefit	0.3	0.8	1.2
Purchase of treasury stock	(5.2)	(3.1)	(0.3)
Purchase of noncontrolling interest	0.0	(1.1)	0.0
Intercompany Activity - Financing	0.0	0.0	0.0
Net cash provided by (used in) financing activities	18.4	(143.6)	(21.4)
Effect of exchange rate changes on cash	0.4	(12.6)	(6.5)
Net increase in cash and cash equivalents	198.7	33.3	95.2
Cash and cash equivalents at beginning of year	282.5	249.2	154.0
Cash and cash equivalents at end of year	481.2	282.5	249.2
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
Purchase buyouts of leased equipment	0.0
Proceeds from government grants	0.0	0.0	0.0
Final distribution of Reserve Yield Plus Fund	0.0
Acquisition of business, net	0.0
Intercompany activity		0.0	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
Employee stock option exercises, including tax benefit	0.0	0.0	0.0
Purchase of treasury stock	(5.2)	(3.1)	(0.3)
Purchase of noncontrolling interest		0.0
Intercompany Activity - Financing	5.2	3.1	0.3
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	78.3	163.7	83.4
Investing activities
Purchases of property, plant and equipment	(36.8)	(36.4)	(51.3)
Proceeds from sale of property, plant and equipment	0.0	0.1	7.9
Purchase buyouts of leased equipment	(4.6)
Proceeds from government grants	0.0	0.0	0.0
Final distribution of Reserve Yield Plus Fund	1.0
Acquisition of business, net	0.0
Intercompany activity		0.0	0.0
Net cash used in investing activities	(40.4)	(36.3)	(43.4)
Financing activities
Net debt activity	(0.7)	(142.8)	(7.8)
Debt issuance costs			(0.3)
Employee stock option exercises, including tax benefit	0.3	0.8	1.2
Purchase of treasury stock	0.0	0.0	0.0
Purchase of noncontrolling interest		0.0
Intercompany Activity - Financing	(5.2)	(3.1)	(0.3)
Net cash provided by (used in) financing activities	(5.6)	(145.1)	(7.2)
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	32.3	(17.7)	32.8
Cash and cash equivalents at beginning of year	52.0	69.7	36.9
Cash and cash equivalents at end of year	84.3	52.0	69.7
Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	25.3	68.1	41.9
Investing activities
Purchases of property, plant and equipment	(18.0)	(12.8)	(18.6)
Proceeds from sale of property, plant and equipment	0.3	0.1	0.4
Purchase buyouts of leased equipment	0.0
Proceeds from government grants	0.0	0.0	0.0
Final distribution of Reserve Yield Plus Fund	0.0
Acquisition of business, net	(5.6)
Intercompany activity		55.0	23.3
Net cash used in investing activities	(23.3)	(67.7)	(41.5)
Financing activities
Net debt activity	(0.4)	(0.4)	(0.4)
Debt issuance costs			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
Purchase of noncontrolling interest		0.0
Intercompany Activity - Financing	0.0	0.0	0.0
Net cash provided by (used in) financing activities	(0.4)	(0.4)	(0.4)
Effect of exchange rate changes on cash	0.0	0.0	0.0
Net increase in cash and cash equivalents	1.6	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	1.6	0.0	0.0
Non-Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	304.0	145.8	193.1
Investing activities
Purchases of property, plant and equipment	(168.2)	(144.3)	(136.6)
Proceeds from sale of property, plant and equipment	1.4	0.1	0.8
Purchase buyouts of leased equipment	0.0
Proceeds from government grants	2.8	5.1	2.1
Final distribution of Reserve Yield Plus Fund	0.0
Acquisition of business, net	0.0
Intercompany activity		0.0	0.0
Net cash used in investing activities	(164.0)	(139.1)	(133.7)
Financing activities
Net debt activity	24.4	3.0	(13.8)
Debt issuance costs			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
Purchase of noncontrolling interest		(1.1)
Intercompany Activity - Financing	0.0	55.0	23.3
Net cash provided by (used in) financing activities	24.4	56.9	9.5
Effect of exchange rate changes on cash	0.4	(12.6)	(6.5)
Net increase in cash and cash equivalents	164.8	51.0	62.4
Cash and cash equivalents at beginning of year	230.5	179.5	117.1
Cash and cash equivalents at end of year	395.3	230.5	179.5
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
Purchase buyouts of leased equipment	0.0
Proceeds from government grants	0.0	0.0
Final distribution of Reserve Yield Plus Fund	0.0
Acquisition of business, net	0.0
Intercompany activity		(55.0)	(23.3)
Net cash used in investing activities	0.0	55.0	23.3
Financing activities
Net debt activity	0.0	0.0	0.0
Debt issuance costs			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
Purchase of noncontrolling interest		0.0
Intercompany Activity - Financing	0.0	(55.0)	(23.3)
Net cash provided by (used in) financing activities	0.0	(55.0)	(23.3)
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