Reconciliation of Weighted Average Shares Used in Calculating Basic and Diluted Earnings Per Share (Detail) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share Disclosure [Line Items]
Basic	73,111	72,151	65,763
Effect of exercise of stock options	1,092	1,863	2,141
Effect of exercise of warrants	56	33
Effect of contingent common stock issuance	36	89	149
Effect of assumed vesting of restricted stock	1,200	577	272
Diluted	75,495	74,713	68,325