Stockholders' Equity (Detail) - Summary of Transactions Relating to Common Stock	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Purchases for treasury		2,148,434
Common Stock [Member]
Balance	156,234,415	156,234,415		156,234,415	156,234,415
Purchases for treasury			[1]
Treasury Stock [Member]
Balance	62,873,100	62,891,251		60,245,718	60,356,672
Issuances under stock plans	(2,756,389)	(3,244,705)		(4,029,673)
Purchases for treasury	2,738,238	5,890,238	[1]	3,918,719

[1] Includes 2,148,434 shares the Company repurchased directly from ValueAct Capital Master Fund, L.P. ("ValueAct") in two separate transactions during 2011. The total cost of the shares repurchased directly from ValueAct was $75.2 million.