Quarterly Information (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 494	$ 459	$ 478	$ 468	$ 588	$ 526	$ 544	$ 506	$ 1,899	$ 2,164	$ 2,156
Gross profit	248	247	236	224	289	264	250	223	955	1,026	1,024
Operating (loss) income	(5)	10	10	(5)	23	14	10	(4)	10	43	68
Net (loss) income	$ (19)	$ 10	$ (1)	$ (10)	$ 15	$ 18	$ 4	$ (7)	$ (20)	$ 30	$ (67)
Net (loss) income per share:
Basic (in usd per share)	$ (0.17)	$ 0.09	$ (0.01)	$ (0.09)	$ 0.13	$ 0.15	$ 0.03	$ (0.06)	$ (0.18)	$ 0.25	$ (0.53)
Diluted (in usd per share)	$ (0.17)	$ 0.09	$ (0.01)	$ (0.09)	$ 0.13	$ 0.15	$ 0.03	$ (0.06)	$ (0.18)	$ 0.25	$ (0.53)