Fair Value Measurements and Derivatives - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		$ 1,670	$ 1,591
Fair Value		1,713	1,608
Other Indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		120	66
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Income Approach Valuation Technique [Member] | Other Indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	[1]	120	66
Fair Value		101	56
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Market Approach Valuation Technique [Member] | Senior Notes Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		1,550	1,525
Fair Value		$ 1,612	$ 1,552

[1] *The carrying value includes the unamortized portion of a fair value adjustment related to a terminated interest rate swap at both dates. At December 31, 2016, the carrying value and fair value also include a financial liability associated with a build-to-suit lease arrangement.