Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Non Variable Interest Entities [Line Items]
Deferred income taxes, net	$ 0		$ 0	$ 970
Valuation allowance	1,157		1,157	7
Valuation Allowance Deferred Tax Asset Change In Amount	1,100	$ 55	1,200
NOL carryforward	2,800		2,800
Foreign tax credit	62		62	7
Alternative minimum tax credit carryforward	$ 26		$ 26	$ 26