Fair Value of Financial Instruments Fair Value of Financial Instruments (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 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	$ 0	$ 0
Cash Surrender Value, Fair Value Disclosure	26,000,000		26,000,000		$ 26,000,000
Long-term Debt	2,325,000,000		2,325,000,000		2,193,000,000
Unamortized Debt Issuance Expense	11,000,000		11,000,000		11,000,000
Long-term Debt, Fair Value	$ 2,885,000,000		2,885,000,000		$ 2,455,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		$ 0	$ 0	$ 0