Capital Actions (Detail) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Capital Actions
Shares acquired for treasury	$ 474	$ 664
November 13, 2013 ASR | March 2013 Repurchase Program
Capital Actions
Repurchase date	Nov. 18, 2013
Shares acquired for treasury	200
Shares repurchased on repurchase date	8,538,423
Shares received from forward contract settlement	1,132,495
Total shares repurchased	9,670,918
Settlement date	Mar. 05, 2014
December 10, 2013 ASR | March 2013 Repurchase Program
Capital Actions
Repurchase date	Dec. 13, 2013
Shares acquired for treasury	456
Shares repurchased on repurchase date	19,084,195
Shares received from forward contract settlement	2,294,932
Total shares repurchased	21,379,127
Settlement date	Mar. 31, 2014
January 28, 2014 ASR | March 2013 Repurchase Program
Capital Actions
Repurchase date	Jan. 31, 2014
Shares acquired for treasury	99
Shares repurchased on repurchase date	3,950,705
Shares received from forward contract settlement	602,109
Total shares repurchased	4,552,814
Settlement date	Mar. 31, 2014
April 28, 2014 ASR | March 2014 Repurchase Program
Capital Actions
Repurchase date	May 01, 2014
Shares acquired for treasury	150
Shares repurchased on repurchase date	6,216,480
Shares received from forward contract settlement	1,016,514
Total shares repurchased	7,232,994
Settlement date	Jul. 21, 2014
July 21, 2014 ASR | March 2014 Repurchase Program
Capital Actions
Repurchase date	Jul. 24, 2014
Shares acquired for treasury	$ 225
Shares repurchased on repurchase date	9,352,078
Shares received from forward contract settlement	1,896,685
Total shares repurchased	11,248,763
Settlement date	Oct. 14, 2014