Stockholders' Equity - Common Stock Activity (Detail)	1 Months Ended								5 Months Ended	9 Months Ended	15 Months Ended
	Sep. 30, 2014	Aug. 31, 2014	Jul. 31, 2014	Jun. 30, 2014	May 31, 2014	Apr. 30, 2014	Mar. 31, 2014	Feb. 28, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014
Actual number of shares of common stock outstanding
Beginning of period										378,635,464
Shares of common stock issued through compensation plans										3,978,073
Shares of common stock issued through business combinations										68,737
Repurchases of common stock	(197,759)	(181,509)	(188,612)	(207,243)	(211,848)	(269,972)	(241,091)	(110,239)	(289,839)	(1,608,273)	(1,898,112)
End of period	381,074,001								378,635,464	381,074,001	381,074,001