Fair Value Measurements and Derivatives - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		$ 2,386	$ 1,793
Fair Value		2,436	1,730
Other indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		63	28
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		1,500	1,500
Fair Value		1,553	1,442
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Term Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value		823	265
Fair Value		825	265
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other indebtedness [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Carrying Value	[1]	63	28
Fair Value		$ 58	$ 23

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