Fair Value Measurements and Derivatives - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	$ 1,793	$ 1,804
Fair Value	1,730	1,889
Term Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	265	275
Other Indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	28	29
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Valuation, Market Approach [Member] | Senior Notes Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	1,500	1,500
Fair Value	1,442	1,592
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Valuation, Market Approach [Member] | Term Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	265	275
Fair Value	265	275
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Valuation, Income Approach [Member] | Other Indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	28	29
Fair Value	$ 23	$ 22