Fair Value Measurements and Derivatives - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	$ 1,606		$ 1,591
Fair Value	1,596		1,608
Other indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	81		66
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	1,525		1,525
Fair Value	1,525		1,552
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	81	[1]	66
Fair Value	$ 71		$ 56

[1] * The carrying value includes the unamortized portion of a fair value adjustment related to a terminated interest rate swap.