Supplemental Guarantor Condensed Consolidating Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 112.8	$ 169.2	$ 217.4	$ 244.6
Accounts receivable, net	501.1	333.3
Inventories, net	203.0	177.2
Other assets, current	89.8	83.4
Total current assets	906.7	763.1
Property, plant and equipment, net	998.1	971.2
Goodwill	156.3	155.9
Other assets, noncurrent, condensed	441.2	438.5
Equity method investments	0	0
Total assets	2,502.3	2,328.7
Accounts payable	433.8	337.1
Other liabilities, current, condensed	208.3	239.0
Total current liabilities	642.1	576.1
Intercompany payable (receivable)	0	0
Long-term debt	1,248.7	1,180.2
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	987.9	992.0
Total liabilities	2,878.7	2,748.3
Total AAM stockholders' deficit	(376.4)	(425.5)
Noncontrolling interest in subsidiaries	0	5.9
Total stockholders’ deficit	(376.4)	(419.6)
Total liabilities and stockholders' deficit	2,502.3	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	49.8	104.8
Other liabilities, noncurrent	0	0
Total liabilities	376.4	425.5
Total AAM stockholders' deficit	(376.4)	(425.5)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(376.4)	(425.5)
Total liabilities and stockholders' deficit	0	0
AAM Inc. [Member]
Cash and cash equivalents	30.2	83.7	80.9	67.6
Accounts receivable, net	118.1	77.1
Inventories, net	41.8	48.2
Other assets, current	25.2	26.5
Total current assets	215.3	235.5
Property, plant and equipment, net	261.0	260.4
Goodwill	0	0
Other assets, noncurrent, condensed	324.0	327.2
Equity method investments	1,080.6	1,015.2
Total assets	1,880.9	1,838.3
Accounts payable	102.2	96.3
Other liabilities, current, condensed	110.2	155.1
Total current liabilities	212.4	251.4
Intercompany payable (receivable)	(392.5)	(368.6)
Long-term debt	1,189.1	1,128.9
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	921.7	931.4
Total liabilities	1,930.7	1,943.1
Total AAM stockholders' deficit	(49.8)	(104.8)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(49.8)	(104.8)
Total liabilities and stockholders' deficit	1,880.9	1,838.3
Guarantor Subsidiaries of Certain Notes [Member]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	29.7	23.3
Inventories, net	34.8	35.3
Other assets, current	1.6	1.7
Total current assets	66.1	60.3
Property, plant and equipment, net	84.0	84.6
Goodwill	147.8	147.8
Other assets, noncurrent, condensed	37.8	35.8
Equity method investments	30.7	26.6
Total assets	366.4	355.1
Accounts payable	45.5	41.0
Other liabilities, current, condensed	3.5	3.0
Total current liabilities	49.0	44.0
Intercompany payable (receivable)	282.5	289.0
Long-term debt	5.8	5.9
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	3.6	3.6
Total liabilities	340.9	342.5
Total AAM stockholders' deficit	25.5	12.6
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	25.5	12.6
Total liabilities and stockholders' deficit	366.4	355.1
Non-Guarantor Subsidiaries [Member]
Cash and cash equivalents	82.6	85.5	136.5	177.0
Accounts receivable, net	353.3	232.9
Inventories, net	126.4	93.7
Other assets, current	63.0	55.2
Total current assets	625.3	467.3
Property, plant and equipment, net	653.1	626.2
Goodwill	8.5	8.1
Other assets, noncurrent, condensed	79.4	75.5
Equity method investments	0	0
Total assets	1,366.3	1,177.1
Accounts payable	286.1	199.8
Other liabilities, current, condensed	94.6	80.9
Total current liabilities	380.7	280.7
Intercompany payable (receivable)	(216.6)	(241.1)
Long-term debt	53.8	45.4
Investment in subsidiaries obligation	0	0
Other liabilities, noncurrent	62.6	57.0
Total liabilities	280.5	142.0
Total AAM stockholders' deficit	1,085.8	1,029.2
Noncontrolling interest in subsidiaries	0	5.9
Total stockholders’ deficit	1,085.8	1,035.1
Total liabilities and stockholders' deficit	1,366.3	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	(1,111.3)	(1,041.8)
Total assets	(1,111.3)	(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	(49.8)	(104.8)
Other liabilities, noncurrent	0	0
Total liabilities	(49.8)	(104.8)
Total AAM stockholders' deficit	(1,061.5)	(937.0)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(1,061.5)	(937.0)
Total liabilities and stockholders' deficit	$ (1,111.3)	$ (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.