Supplemental Guarantor Condensed Consolidating Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Current Assets
Cash and cash equivalents	$ 118.6	$ 62.4	$ 209.0	$ 169.2
Accounts receivable, net	596.9	463.4
Inventories, net	251.5	224.3
Other current assets	124.7	122.0
Total current assets	1,091.7	872.1
Property, plant and equipment, net	1,041.8	1,009.7
Goodwill	156.5	156.4
Other assets and deferred charges, condensed	828.5	827.8
Investment in subsidiaries	0	0
Total assets	3,118.5	2,866.0
Current Liabilities
Accounts payable	485.0	396.1
Other current liabilities	219.1	204.7
Total current liabilities	704.1	600.8
Intercompany payable (receivable)	0	0
Long-term debt	1,572.6	1,454.1
Investment in subsidiaries obligation		0
Other long-term liabilities	888.6	931.9
Total liabilities	3,165.3	2,986.8
Total AAM stockholders' equity (deficit)	(46.8)	(120.8)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(46.8)	(120.8)
Total liabilities and stockholders' deficit	3,118.5	2,866.0
Holdings [Member]
Current Assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Inventories, net	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Other assets and deferred charges, condensed	0	0
Investment in subsidiaries	277.3	202.9
Total assets	277.3	202.9
Current Liabilities
Accounts payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany payable (receivable)	324.1	323.7
Long-term debt	0	0
Investment in subsidiaries obligation		0
Other long-term liabilities	0	0
Total liabilities	324.1	323.7
Total AAM stockholders' equity (deficit)	(46.8)	(120.8)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(46.8)	(120.8)
Total liabilities and stockholders' deficit	277.3	202.9
AAM Inc. [Member]
Current Assets
Cash and cash equivalents	25.1	10.6	151.8	83.7
Accounts receivable, net	124.6	94.4
Inventories, net	55.1	48.7
Other current assets	43.6	48.8
Total current assets	248.4	202.5
Property, plant and equipment, net	244.0	250.4
Goodwill	0	0
Other assets and deferred charges, condensed	694.2	706.1
Investment in subsidiaries	1,193.9	1,094.6
Total assets	2,380.5	2,253.6
Current Liabilities
Accounts payable	106.2	91.4
Other current liabilities	120.4	124.5
Total current liabilities	226.6	215.9
Intercompany payable (receivable)	(423.9)	(420.6)
Long-term debt	1,487.9	1,387.5
Investment in subsidiaries obligation		0
Other long-term liabilities	812.6	867.9
Total liabilities	2,103.2	2,050.7
Total AAM stockholders' equity (deficit)	277.3	202.9
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	277.3	202.9
Total liabilities and stockholders' deficit	2,380.5	2,253.6
Guarantor Subsidiaries [Member]
Current Assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	32.1	25.3
Inventories, net	32.3	31.6
Other current assets	3.7	3.5
Total current assets	68.1	60.4
Property, plant and equipment, net	80.4	84.2
Goodwill	147.8	147.8
Other assets and deferred charges, condensed	44.4	40.0
Investment in subsidiaries	0.3	0
Total assets	341.0	332.4
Current Liabilities
Accounts payable	49.1	37.3
Other current liabilities	4.7	3.8
Total current liabilities	53.8	41.1
Intercompany payable (receivable)	(209.3)	(188.7)
Long-term debt	5.4	5.6
Investment in subsidiaries obligation		7.6
Other long-term liabilities	0.7	1.2
Total liabilities	(149.4)	(133.2)
Total AAM stockholders' equity (deficit)	490.4	465.6
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	490.4	465.6
Total liabilities and stockholders' deficit	341.0	332.4
Non-Guarantor Subsidiaries [Member]
Current Assets
Cash and cash equivalents	93.5	51.8	57.2	85.5
Accounts receivable, net	440.2	343.7
Inventories, net	164.1	144.0
Other current assets	77.4	69.7
Total current assets	775.2	609.2
Property, plant and equipment, net	717.4	675.1
Goodwill	8.7	8.6
Other assets and deferred charges, condensed	89.9	81.7
Investment in subsidiaries	0	0
Total assets	1,591.2	1,374.6
Current Liabilities
Accounts payable	329.7	267.4
Other current liabilities	94.0	76.4
Total current liabilities	423.7	343.8
Intercompany payable (receivable)	309.1	285.6
Long-term debt	79.3	61.0
Investment in subsidiaries obligation		0
Other long-term liabilities	75.3	62.8
Total liabilities	887.4	753.2
Total AAM stockholders' equity (deficit)	703.8	621.4
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	703.8	621.4
Total liabilities and stockholders' deficit	1,591.2	1,374.6
Elims [Member]
Current Assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Inventories, net	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill	0	0
Other assets and deferred charges, condensed	0	0
Investment in subsidiaries	(1,471.5)	(1,297.5)
Total assets	(1,471.5)	(1,297.5)
Current Liabilities
Accounts payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany payable (receivable)	0	0
Long-term debt	0	0
Investment in subsidiaries obligation		(7.6)
Other long-term liabilities	0	0
Total liabilities	0	(7.6)
Total AAM stockholders' equity (deficit)	(1,471.5)	(1,289.9)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(1,471.5)	(1,289.9)
Total liabilities and stockholders' deficit	$ (1,471.5)	$ (1,297.5)

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.