Total Outstanding Shares (Detail)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Class of Stock [Line Items]
Beginning Balance	141,735,000	146,961,000	148,528,000
Shares Issued	2,084,000	1,489,000	886,000
Repurchase of common stock at cost	(2,187,382)	(6,714,508)	(2,453,000)
Ending Balance	141,632,000	141,735,000	146,961,000
Common Stock
Class of Stock [Line Items]
Beginning Balance	162,776,000	162,776,000	162,776,000
Shares Issued	0	0	0
Repurchase of common stock at cost	0	0	0
Ending Balance	162,776,000	162,776,000	162,776,000
Treasury Stock
Class of Stock [Line Items]
Beginning Balance	(21,041,000)	(15,815,000)	(14,248,000)
Shares Issued	2,084,000	1,489,000	886,000
Repurchase of common stock at cost	(2,187,000)	(6,715,000)	(2,453,000)
Ending Balance	(21,144,000)	(21,041,000)	(15,815,000)