Comprehensive Income (Loss) (Summary Of The Activity In Other Comprehensive Income (Loss), Net Of The Related Tax Effects) (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period	$ 5	$ 5		$ 5
Reclassification of unrealized gain/loss on equity securities	(2)
Reclassification of tax rate change	4
Other comprehensive income before reclassifications:
Pre-tax amount		3		1
Tax provision		5		1
After-tax amount		8
Amounts reclassified from accumulated Other Comprehensive Income (Loss)		(4)	[1]	(3)
Net current period other comprehensive income		4		(3)	$ 8
Balance at the end of period	7	9		5	5
Unrealized Gains (Losses) on Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period	16	20		16
Reclassification of tax rate change	3
Other comprehensive income before reclassifications:
Pre-tax amount		(7)		4
Tax provision		5		1
After-tax amount		(2)		3
Amounts reclassified from accumulated Other Comprehensive Income (Loss)		(4)	[1]	(3)
Net current period other comprehensive income		(6)		1
Balance at the end of period	19	13		20	16
Unrealized Gains on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period	2			2
Reclassification of unrealized gain/loss on equity securities	(2)
Reclassification of tax rate change	1
Other comprehensive income before reclassifications:
Balance at the end of period					2
Foreign Currency Translation (Loss) Gain [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at the beginning of period	(12)	(15)		(12)
Other comprehensive income before reclassifications:
Pre-tax amount		10		(3)
After-tax amount		10		(3)
Net current period other comprehensive income		10		(3)
Balance at the end of period	$ (12)	$ (5)		$ (15)	$ (12)

[1] Amounts are net of tax. See reclassifications out of accumulated other comprehensive income below for further details.