Capital Actions (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Capital Actions
Shares acquired for treasury	$ 335	$ 249
October 20, 2014 ASR | March 2014 Repurchase Program
Capital Actions
Repurchase date	Oct. 23, 2014
Shares acquired for treasury	$ 180
Shares repurchased on repurchase date	8,337,875
Shares received from forward contract settlement	794,245
Total shares repurchased	9,132,120
Settlement date	Jan. 08, 2015
January 22, 2015 ASR | March 2014 Repurchase Program
Capital Actions
Repurchase date	Jan. 27, 2015
Shares acquired for treasury	$ 180
Shares repurchased on repurchase date	8,542,713
Shares received from forward contract settlement	1,103,744
Total shares repurchased	9,646,457
Settlement date	Apr. 28, 2015
April 27, 2015 ASR | March 2014 Repurchase Program
Capital Actions
Repurchase date	Apr. 30, 2015
Shares acquired for treasury	$ 155
Shares repurchased on repurchase date	6,704,835
Shares received from forward contract settlement	842,655
Total shares repurchased	7,547,490
Settlement date	Jul. 31, 2015