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
		Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period		$ 9	$ 5
Other comprehensive income before reclassifications:
Pre-tax amount		(61)	(7)
Tax provision		12	5
After-tax amount		(49)	(1)
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	(1)
Net current period other comprehensive (loss) income		(50)	(2)
Balance at the end of period		(41)	3
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period		13	20
Other comprehensive income before reclassifications:
Pre-tax amount		(45)	(7)
Tax provision		12	5
After-tax amount		(34)	(2)
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	(1)
Net current period other comprehensive (loss) income		(34)	(3)
Balance at the end of period		(21)	17
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period		(5)	(15)
Other comprehensive income before reclassifications:
Pre-tax amount		(15)	1
After-tax amount		(15)	1
Net current period other comprehensive (loss) income		(15)	1
Balance at the end of period		$ (20)	$ (14)

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