Income Taxes Income Taxes - Deferred Income Tax Valuation Allowance Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Beginning balance of deferred income tax valuation allowance	$ 95	$ 11	$ 16
Additions charged to costs and expenses	0	0	5
Additions charged against goodwill	0	84	0
Deductions	(20)	0	(10)
Ending balance of deferred income tax valuation allowance	$ 75	$ 95	$ 11