Redeemable Noncontrolling Interests (Redeemable Noncontrolling Interests Rollforward) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Beginning balance	$ 411,000,000	$ 512,000,000
RGNext initial recognition	32,000,000
Net income (loss)	(14,000,000)	(27,000,000)
Other comprehensive income (loss), net of tax(1)	0	(1,000,000)
Distributions related to noncontrolling interest	(5,000,000)
Adjustment of noncontrolling interests to redemption value	(1,000,000)	(73,000,000)
Acquisition of noncontrolling interest in Forcepoint	(391,000,000)
Ending balance	32,000,000	411,000,000
Forcepoint
Noncontrolling Interest [Line Items]
Beginning balance	411,000,000	512,000,000
RGNext initial recognition	0
Net income (loss)	(19,000,000)	(27,000,000)
Other comprehensive income (loss), net of tax(1)	0	(1,000,000)
Distributions related to noncontrolling interest	0
Adjustment of noncontrolling interests to redemption value	(1,000,000)	(73,000,000)
Acquisition of noncontrolling interest in Forcepoint	(391,000,000)
Ending balance	0	411,000,000
Forcepoint | Maximum [Member]
Noncontrolling Interest [Line Items]
Other comprehensive income (loss), net of tax(1)	1,000,000
RGNext [Member]
Noncontrolling Interest [Line Items]
Beginning balance	0	0
RGNext initial recognition	32,000,000
Net income (loss)	5,000,000	0
Other comprehensive income (loss), net of tax(1)	0	0
Distributions related to noncontrolling interest	(5,000,000)
Adjustment of noncontrolling interests to redemption value	0	0
Acquisition of noncontrolling interest in Forcepoint	0
Ending balance	$ 32,000,000	$ 0