Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ 2,224	$ 2,577		$ 2,043
Total other comprehensive income, net of tax	[1]	2	17	[2]	13	[2]
Impact of disposal of Canadian Holdings	[1]	107
Ending Balance	[1]	5,538	2,224		2,577
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(127)	(144)		(157)
Ending Balance		(18)	(127)		(144)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		1	(4)		(11)
Amounts reclassified from AOCI to interest expense		2	5		7
Total other comprehensive income, net of tax		2	5		7
Impact of disposal of Canadian Holdings		3
Ending Balance		6	1		(4)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(98)	(105)		(108)
Other comprehensive loss before reclassification		(6)	7		3
Total other comprehensive income, net of tax		(6)	7		3
Impact of disposal of Canadian Holdings		104
Ending Balance		0	(98)		(105)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(30)	(35)		(38)
Other comprehensive loss before reclassification		6	5		3
Total other comprehensive income, net of tax		6	5		3
Ending Balance		(24)	$ (30)		$ (35)
AOCI Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		(12)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		5
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		0
Accumulated Net Investment Gain (Loss) Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		(17)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		(6)
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		1
Net Unrealized Gains (Losses) on Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		0
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending Balance		$ (7)

[1] Prior-period financial information has been retrospectively adjusted as discussed in Note 14.

[2] Prior-period financial information has been retrospectively adjusted as discussed in Note 14.