Fair Value of Financial Instruments Fair Value of Financial Instruments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0	$ 0
Cash Surrender Value, Fair Value Disclosure	25,000,000		$ 26,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0	$ 0
Long-term Debt	2,199,000,000		2,193,000,000
Unamortized Debt Issuance Expense	12,000,000		11,000,000
Long-term Debt, Fair Value	$ 2,617,000,000		$ 2,455,000,000