Stockholders' Equity - Common Stock Activity (Detail)	1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 31, 2014	Feb. 28, 2014	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Actual number of shares of common stock outstanding
Beginning of period			378,635,464
Shares of common stock issued through compensation plans			610,020
Shares of common stock issued through business combinations			21,136
Repurchases of common stock	(241,091)	(110,239)	(351,330)	(641,169)	(289,839)
End of period	378,915,290		378,915,290		378,635,464