Fair Value of Financial Instruments Fair Value of Financial Instruments (Details) - USD ($)	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	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	26,000,000		$ 26,000,000
Long-term Debt	2,324,000,000		2,193,000,000
Unamortized Debt Issuance Expense		$ 12,000,000	11,000,000
Long-term Debt, Fair Value	$ 2,908,000,000		$ 2,455,000,000