Schedule Of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)									$ 192	$ (51)	$ (58)
Net revenues	$ 2,019	$ 2,752	$ 2,238	$ 1,839	$ 1,879	$ 2,656	$ 2,243	$ 1,881
Net income (loss)	$ 220	$ 245	$ 3	$ (107)	$ (31)	$ 209	$ 36	$ (51)
Basic Net income (loss) (in dollars per share)	$ 2.70	$ 2.96	$ 0.04	$ (1.25)	$ (0.35)	$ 2.32	$ 0.39	$ (0.53)	$ 4.32	$ 1.78	$ 3.02
Basic weighted average shares outstanding	81.3	82.6	84.0	85.7	87.4	90.4	93.9	96.3	83.4	92.0	103.4
Diluted Net income (loss) (in dollars per share)	$ 2.65	$ 2.91	$ 0.04	$ (1.25)	$ (0.35)	$ 2.28	$ 0.38	$ (0.53)	$ 4.25	$ 1.75	$ 2.98
Diluted weighted average shares outstanding	82.7	84.0	85.2	85.7	87.4	91.8	95.1	96.3	84.8	93.3	105.0
Provision adjustment due to anticipated repatriation of foreign earnings [Member]
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)									$ (104)
Provision adjustment due to corporate tax rate change [Member]
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)									$ 317