Segment Information - Revenues By Geographic Area (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Total consolidated revenues	$ 7,014	$ 6,079	$ 5,997	$ 5,613	$ 7,048	$ 6,032	$ 5,880	$ 5,479	$ 24,704	$ 24,440	$ 23,222
UNITED STATES
Segment Reporting Information [Line Items]
Total consolidated revenues									13,361	12,835	12,230
Europe, Middle East and Africa
Segment Reporting Information [Line Items]
Total consolidated revenues									6,845	6,981	6,355
Asia Pacific and Japan
Segment Reporting Information [Line Items]
Total consolidated revenues									3,157	3,191	3,193
Latin America, Mexico and Canada
Segment Reporting Information [Line Items]
Total consolidated revenues									$ 1,341	$ 1,433	$ 1,444