Supplemental Guarantor Condensed Consolidating Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 209.0	$ 169.2	$ 114.4	$ 244.6
Accounts receivable, net	465.3	333.3
Inventories, net	242.3	177.2
Other assets, current	105.5	83.4
Total current assets	1,022.1	763.1
Property, plant and equipment, net	1,007.6	971.2
Goodwill	156.3	155.9
Other assets, noncurrent, condensed	488.2	438.5
Equity method investments	0	0
Total assets	2,674.2	2,328.7
Accounts payable	429.5	337.1
Other liabilities, current, condensed	220.3	239.0
Total current liabilities	649.8	576.1
Intercompany payable (receivable)	0	0
Long-term debt	1,579.9	1,180.2
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	942.2	992.0
Total liabilities	3,171.9	2,748.3
Total AAM stockholders' deficit	(497.7)	(425.5)
Noncontrolling interest in subsidiaries	0	5.9
Total stockholders’ deficit	(497.7)	(419.6)
Total liabilities and stockholders' deficit	2,674.2	2,328.7
Holdings [Member]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Inventories, net	0	0
Other assets, current	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Other assets, noncurrent, condensed	0	0
Equity method investments	0	0
Total assets	0	0
Accounts payable	0	0
Other liabilities, current, condensed	0	0
Total current liabilities	0	0
Intercompany payable (receivable)	326.6	320.7
Long-term debt	0	0
Investment in subsidiaries obligation	171.1	104.8
Other liabilities, noncurrent	0	0
Total liabilities	497.7	425.5
Total AAM stockholders' deficit	(497.7)	(425.5)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(497.7)	(425.5)
Total liabilities and stockholders' deficit	0	0
AAM Inc. [Member]
Cash and cash equivalents	151.8	83.7	40.9	67.6
Accounts receivable, net	84.9	77.1
Inventories, net	51.2	48.2
Other assets, current	32.1	26.5
Total current assets	320.0	235.5
Property, plant and equipment, net	258.4	260.4
Goodwill	0	0
Other assets, noncurrent, condensed	360.8	327.2
Equity method investments	1,151.0	1,015.2
Total assets	2,090.2	1,838.3
Accounts payable	95.9	96.3
Other liabilities, current, condensed	128.1	155.1
Total current liabilities	224.0	251.4
Intercompany payable (receivable)	(392.4)	(368.6)
Long-term debt	1,541.6	1,128.9
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	888.1	931.4
Total liabilities	2,261.3	1,943.1
Total AAM stockholders' deficit	(171.1)	(104.8)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(171.1)	(104.8)
Total liabilities and stockholders' deficit	2,090.2	1,838.3
Guarantor Subsidiaries of Certain Notes [Member]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	30.9	23.3
Inventories, net	33.1	35.3
Other assets, current	1.7	1.7
Total current assets	65.7	60.3
Property, plant and equipment, net	84.3	84.6
Goodwill	147.8	147.8
Other assets, noncurrent, condensed	39.4	35.8
Equity method investments	4.3	26.6
Total assets	341.5	355.1
Accounts payable	47.4	41.0
Other liabilities, current, condensed	3.8	3.0
Total current liabilities	51.2	44.0
Intercompany payable (receivable)	275.2	289.0
Long-term debt	5.7	5.9
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	3.6	3.6
Total liabilities	335.7	342.5
Total AAM stockholders' deficit	5.8	12.6
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	5.8	12.6
Total liabilities and stockholders' deficit	341.5	355.1
Non-Guarantor Subsidiaries [Member]
Cash and cash equivalents	57.2	85.5	73.5	177.0
Accounts receivable, net	349.5	232.9
Inventories, net	158.0	93.7
Other assets, current	71.7	55.2
Total current assets	636.4	467.3
Property, plant and equipment, net	664.9	626.2
Goodwill	8.5	8.1
Other assets, noncurrent, condensed	88.0	75.5
Equity method investments	0	0
Total assets	1,397.8	1,177.1
Accounts payable	286.2	199.8
Other liabilities, current, condensed	88.4	80.9
Total current liabilities	374.6	280.7
Intercompany payable (receivable)	(209.4)	(241.1)
Long-term debt	32.6	45.4
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	50.5	57.0
Total liabilities	248.3	142.0
Total AAM stockholders' deficit	1,149.5	1,029.2
Noncontrolling interest in subsidiaries	0	5.9
Total stockholders’ deficit	1,149.5	1,035.1
Total liabilities and stockholders' deficit	1,397.8	1,177.1
Consolidation, Eliminations [Member]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Inventories, net	0	0
Other assets, current	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Other assets, noncurrent, condensed	0	0
Equity method investments	(1,155.3)	(1,041.8)
Total assets	(1,155.3)	(1,041.8)
Accounts payable	0	0
Other liabilities, current, condensed	0	0
Total current liabilities	0	0
Intercompany payable (receivable)	0	0
Long-term debt	0	0
Investment in subsidiaries obligation	(171.1)	(104.8)
Other liabilities, noncurrent	0	0
Total liabilities	(171.1)	(104.8)
Total AAM stockholders' deficit	(984.2)	(937.0)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(984.2)	(937.0)
Total liabilities and stockholders' deficit	$ (1,155.3)	$ (1,041.8)

This element represents the net payables/(receivables) arising from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, such as pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's' management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

No definition available.