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						9 Months Ended
		Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 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								(73)	(16)
Tax provision								12	7
After-tax amount								(61)	(9)
Amounts reclassified from accumulated other comprehensive (loss) income	[1]							3	(3)
Net current period other comprehensive (loss) income		$ (10)	$ 1	(50)	$ (7)	$ (4)	(2)	(58)	(13)
Balance at the end of period		(49)			(8)			(49)	(8)
Unrealized Gains (Losses) On Derivatives [Member]
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								(66)	(14)
Tax provision								12	7
After-tax amount								(54)	(7)
Amount reclassified within accumulated other comprehensive (loss) income	[2]							17
Amounts reclassified from accumulated other comprehensive (loss) income	[1]							3	(3)
Net current period other comprehensive (loss) income								(34)	(10)
Balance at the end of period		(21)			9			(21)	9
Foreign Currency Translation [Member]
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								(7)	(2)
After-tax amount								(7)	(2)
Amount reclassified within accumulated other comprehensive (loss) income	[2]							(17)
Net current period other comprehensive (loss) income								(24)	(2)
Balance at the end of period		$ (29)			$ (18)			$ (29)	$ (18)

[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.