Qualifying And Valuation Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 110	$ 120	$ 127
Additions Charged to costs and expenses	18	4	4
(Credited) charged to other accounts	(8)	(7)	8
Deductions	(8)	(7)	(19)
Balance at end of period	112	110	120
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	310	483	150
Additions Charged to costs and expenses	117	20	350
(Credited) charged to other accounts	0	(4)	0
Deductions	(7)	(189)	(17)
Balance at end of period	$ 420	$ 310	$ 483