Capital Actions (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Capital Actions [Line Items]
Shares acquired for treasury	$ 240	$ 180
December 10, 2015 ASR | March 2014 Repurchase Program
Capital Actions [Line Items]
Repurchase date	Dec. 14, 2015
Shares acquired for treasury	$ 215
Shares repurchased on repurchase date	9,248,482
Shares received from forward contract settlement	1,782,477
Total shares repurchased	11,030,959
Settlement date	Jan. 14, 2016
March 2, 2016 ASR | March 2014 Repurchase Program
Capital Actions [Line Items]
Repurchase date	Mar. 04, 2016
Shares acquired for treasury	$ 240
Shares repurchased on repurchase date	12,623,762
Shares received from forward contract settlement	1,868,379
Total shares repurchased	14,492,141
Settlement date	Apr. 11, 2016