Employee Benefit Plans - GM Cost Sharing Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Total GM postretirement cost sharing asset	$ 250.0	$ 236.0
Current GM postretirement cost sharing asset	13.0
Noncurrent GM postretirement cost sharing asset	$ 237.0	$ 223.3

Amounts estimated to be received from General Motors Company (GM), beyond one year of the balance sheet date, that relate to an agreement between us and GM to share proportionally in the cost of other postretirement employee benefits for eligible retirees based on the length of service an employee had with us and GM.

No definition available.

Name:	axl_GmPostretirementCostSharingAssetNoncurrent
Namespace Prefix:	axl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant