Acquisition of Businesses Pro Forma Table - Acquisition (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Revenues	$ 1,101	$ 867	$ 836	$ 540	$ 528	$ 515	$ 487	$ 431	$ 3,344	$ 1,960	$ 1,410
Net income	121	161	178	106	91	124	136	112	566	463	386
Business Acquisition, Pro Forma Revenue									4,201	3,865
Business Acquisition, Pro Forma Net Income (Loss)									712	687
Ally FInancial [Member] | International [Member]
Business Acquisition [Line Items]
Revenues									968
Net income									$ 109