Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Deferred income tax liability on undistributed foreign earnings	$ 1,903	$ 1,654
Deferred income tax expense on foreign undistributed earnings		311	$ 225
Non-cash ceiling test write-downs due to change in deferred tax position	19
Foreign tax credit carryforward, amount	2,090
Tax expense (benefit) recorded	1	(1)	1
Accrued for payment of interest and penalties	1	0	1
Reserve for uncertain tax positions related to the current year	19
Settlements	3
Increase in valuation allowances	5,500	418	$ 232
United States [Member]
Income Tax [Line Items]
Current income tax liability	560
Deferred income tax liability on undistributed foreign earnings		$ 560
United States [Member]
Income Tax [Line Items]
Operating loss carryforwards	198
Canada [Member]
Income Tax [Line Items]
Operating loss carryforwards	60
Capital loss carryforwards	$ 848