Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Income Taxes [Line Items]
Provision for income taxes	$ 15,977,000	$ 10,294,000	$ 29,401,000	$ 18,457,000
Effective tax rate	33.10%	33.90%	32.40%	31.80%
Gross unrecognized tax benefits	17,800,000		17,800,000		15,800,000
Increase due to gross unrecognized tax benefits recorded			2,000,000
Decrease in gross unrecognized tax benefits due to settlements of outstanding audits and the expiration of the statutes of limitation			1,200,000
Long term uncertain tax positions	$ 16,600,000		$ 16,600,000		$ 15,700,000