Income Taxes - Narrative (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended
	Dec. 31, 2014		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Income Taxes [Line Items]
Undistributed earnings of foreign subsidiaries	$ 26		$ 26		$ 115
Net operating loss carryforward	205	[1]	205	[1]	254	[1]
Valuation allowance	57		57		104
Unrecognized tax benefits that would impact effective tax rate	71		71		104		28
Penalties and interest expense			(12)		(7)		5
Penalties accrued	125		125		149
Gross unrecognized tax benefits could decrease, lower bound	20		20
Gross unrecognized tax benefits could decrease, upper bound	31		31
Deposit to reduce unrecognized tax benefit liabilities	22		22		44
Contributions from GM	700
Related party taxes payable	636		636		643
Tax Year 2035 [Member]
Income Taxes [Line Items]
Net operating loss carryforward	58		58
Expiring Indefinitely [Member]
Income Taxes [Line Items]
Net operating loss carryforward	147		147
U.S. [Member]
Income Taxes [Line Items]
Deferral period			4 years
U.S. [Member] | Tax Year 2010 [Member]
Income Taxes [Line Items]
Contributions from GM			30
U.S. [Member] | Tax Year 2011 [Member]
Income Taxes [Line Items]
Contributions from GM			266
Foreign Tax Authority [Member]
Income Taxes [Line Items]
Valuation allowance	$ 57		$ 57

[1] Includes tax-effected operating losses of $58 million expiring through 2035 and $147 million that may be carried forward indefinitely at December 31, 2014.