Comprehensive (Loss) Income (Summary Of The Activity In Other Comprehensive Income (Loss), Net Of The Related Tax Effects) (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period			$ 9		$ 5	$ 9	$ 5
Other comprehensive income before reclassifications:
Pre-tax amount						(61)	(9)
Tax provision						12	6
After-tax amount						(50)	(3)
Amounts reclassified from accumulated other comprehensive (loss) income	[1]					1	(2)
Net current period other comprehensive (loss) income		$ 1	(50)	$ (4)	(2)	(48)	(5)
Balance at the end of period		(40)		(1)		(40)	(1)
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period			13		20	13	20
Other comprehensive income before reclassifications:
Pre-tax amount						(55)	(11)
Tax provision						12	6
After-tax amount						(44)	(5)
Amount reclassified within accumulated other comprehensive (loss) income	[2]					10
Amounts reclassified from accumulated other comprehensive (loss) income	[1]					1	(2)
Net current period other comprehensive (loss) income						(33)	(7)
Balance at the end of period		(19)		13		(19)	13
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period			$ (5)		$ (15)	(5)	(15)
Other comprehensive income before reclassifications:
Pre-tax amount						(6)	2
After-tax amount						(6)	2
Amount reclassified within accumulated other comprehensive (loss) income	[2]					(10)
Net current period other comprehensive (loss) income						(16)	2
Balance at the end of period		$ (20)		$ (13)		$ (20)	$ (13)

[1] Amounts are net of tax. Reclassifications out of accumulated other comprehensive (loss) income included the following components for the periods indicated

[2] Represents unrealized gains (losses) on our cross currency swap and net investment hedge related to foreign currency exchange rate fluctuations.