Schedule Of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Millions, $ 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
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)									$ 103	$ (14)	$ 192
Revenues	$ 2,162	$ 2,753	$ 2,337	$ 1,920	$ 2,050	$ 2,778	$ 2,328	$ 1,968	9,172	9,124	8,848
Net income	$ 142	$ 189	$ 62	$ (91)	$ 13	$ 213	$ 26	$ (87)	$ 302	$ 165	$ 361
Basic Net income (loss) (in dollars per share)	$ 1.92	$ 2.52	$ 0.81	$ (1.20)	$ 0.16	$ 2.71	$ 0.33	$ (1.08)	$ 4.01	$ 2.08	$ 4.32
Basic weighted average shares outstanding	73.9	75.2	76.0	75.8	76.9	78.8	80.7	81.0	75.2	79.3	83.4
Diluted Net income (loss) (in dollars per share)	$ 1.90	$ 2.50	$ 0.81	$ (1.20)	$ 0.16	$ 2.68	$ 0.32	$ (1.08)	$ 3.98	$ 2.06	$ 4.25
Diluted weighted average shares outstanding	74.4	75.7	76.4	75.8	77.6	79.5	81.5	81.0	75.7	80.1	84.8
Provision adjustment due to anticipated repatriation of foreign earnings [Member]
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)		$ (30)									$ (104)