Related Party Transactions (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Mar. 31, 2016
Related Party Transaction [Line Items]
Finance receivable repayment period	30 days
Adam Opel AG [Member]
Related Party Transaction [Line Items]
Commercial loan funding payable		$ 456
General Motors [Member]
Related Party Transaction [Line Items]
Maximum borrowing capacity		4,000
Junior Subordinated Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Line of credit facilities - GM Related party facility		$ 1,000