Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Summary of Significant Accounting Policies [Line Items]
Intercompany Subvention Receivable	$ 45.7	$ 20.8
Intercompany Receivable - Commercial Lending	$ 47.2	$ 45.6

Total amount due to the entity, as of the balance sheet date, from the Parent Company as a result of an agreement with the Parent Company to provide cash payments to the entity to offer lower interest rates on finance and lease contracts.

No definition available.

Name:	acf_IntercompanySubventionReceivable
Namespace Prefix:	acf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant