Supplemental Guarantor Condensed Consolidating Financial Statements 2012 and 2011 Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current Assets
Cash and Cash Equivalents	$ 62.4	$ 169.2	$ 244.6	$ 178.1
Accounts receivable, net	463.4	333.3
Inventories, net	224.3	177.2
Other current assets	122.0	83.4
Total current assets	872.1	763.1
Property, Plant and Equipment, Net	1,009.7	971.2
Goodwill	156.4	155.9	155.8
Other assets and deferred charges	827.8	438.5
Investment in subsidiaries	0	0
Total assets	2,866.0	2,328.7
Current Liabilities
Accounts Payable	396.1	337.1
Other current liabilities	204.7	239.0
Total current liabilities	600.8	576.1
Intercompany Payable (Receivable)	0	0
Long-term debt	1,454.1	1,180.2
Investment in Subsidiaries Obligation	0	0
Other Liabilities, Noncurrent	931.9	992.0
Total liabilities	2,986.8	2,748.3
Total AAM Stockholders' equity (deficit)	(120.8)	(425.5)
Noncontrolling interest in subsidiaries	0	5.9	11.4	0.3
Total stockholders’ deficit	(120.8)	(419.6)
Total liabilities and stockholders' deficit	2,866.0	2,328.7
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	0	0
Investment in subsidiaries	202.9	0
Total assets	202.9	0
Current Liabilities
Accounts Payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany Payable (Receivable)	323.7	320.7
Long-term debt	0	0
Investment in Subsidiaries Obligation	0	104.8
Other Liabilities, Noncurrent	0	0
Total liabilities	323.7	425.5
Total AAM Stockholders' equity (deficit)	(120.8)	(425.5)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(120.8)	(425.5)
Total liabilities and stockholders' deficit	202.9	0
AAM Inc. [Member]
Current Assets
Cash and Cash Equivalents	10.6	83.7	67.6	80.6
Accounts receivable, net	94.4	77.1
Inventories, net	48.7	48.2
Other current assets	48.8	26.5
Total current assets	202.5	235.5
Property, Plant and Equipment, Net	250.4	260.4
Goodwill	0	0
Other assets and deferred charges	706.1	327.2
Investment in subsidiaries	1,094.6	1,015.2
Total assets	2,253.6	1,838.3
Current Liabilities
Accounts Payable	91.4	96.3
Other current liabilities	124.5	155.1
Total current liabilities	215.9	251.4
Intercompany Payable (Receivable)	(420.6)	(368.6)
Long-term debt	1,387.5	1,128.9
Investment in Subsidiaries Obligation	0	0
Other Liabilities, Noncurrent	867.9	931.4
Total liabilities	2,050.7	1,943.1
Total AAM Stockholders' equity (deficit)	202.9	(104.8)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	202.9	(104.8)
Total liabilities and stockholders' deficit	2,253.6	1,838.3
Guarantor Subsidiaries of Certain Notes [Member]
Current Assets
Cash and Cash Equivalents	0	0	0	1.9
Accounts receivable, net	25.3	23.3
Inventories, net	31.6	35.3
Other current assets	3.5	1.7
Total current assets	60.4	60.3
Property, Plant and Equipment, Net	84.2	84.6
Goodwill	147.8	147.8
Other assets and deferred charges	40.0	35.8
Investment in subsidiaries	0	26.6
Total assets	332.4	355.1
Current Liabilities
Accounts Payable	37.3	41.0
Other current liabilities	3.8	3.0
Total current liabilities	41.1	44.0
Intercompany Payable (Receivable)	(188.7)	289.0
Long-term debt	5.6	5.9
Investment in Subsidiaries Obligation	7.6	0
Other Liabilities, Noncurrent	1.2	3.6
Total liabilities	(133.2)	342.5
Total AAM Stockholders' equity (deficit)	465.6	12.6
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	465.6	12.6
Total liabilities and stockholders' deficit	332.4	355.1
Non-Guarantor Subsidiaries [Member]
Current Assets
Cash and Cash Equivalents	51.8	85.5	177.0	95.6
Accounts receivable, net	343.7	232.9
Inventories, net	144.0	93.7
Other current assets	69.7	55.2
Total current assets	609.2	467.3
Property, Plant and Equipment, Net	675.1	626.2
Goodwill	8.6	8.1
Other assets and deferred charges	81.7	75.5
Investment in subsidiaries	0	0
Total assets	1,374.6	1,177.1
Current Liabilities
Accounts Payable	267.4	199.8
Other current liabilities	76.4	80.9
Total current liabilities	343.8	280.7
Intercompany Payable (Receivable)	285.6	(241.1)
Long-term debt	61.0	45.4
Investment in Subsidiaries Obligation	0	0
Other Liabilities, Noncurrent	62.8	57.0
Total liabilities	753.2	142.0
Total AAM Stockholders' equity (deficit)	621.4	1,029.2
Noncontrolling interest in subsidiaries	0	5.9
Total stockholders’ deficit	621.4	1,035.1
Total liabilities and stockholders' deficit	1,374.6	1,177.1
Consolidation, Eliminations [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	0	0
Investment in subsidiaries	(1,297.5)	(1,041.8)
Total assets	(1,297.5)	(1,041.8)
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)	(104.8)
Other Liabilities, Noncurrent	0	0
Total liabilities	(7.6)	(104.8)
Total AAM Stockholders' equity (deficit)	(1,289.9)	(937.0)
Noncontrolling interest in subsidiaries	0	0
Total stockholders’ deficit	(1,289.9)	(937.0)
Total liabilities and stockholders' deficit	$ (1,297.5)	$ (1,041.8)