Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Income Taxes [Line Items]
Provision for income taxes	$ 19,009,000	$ 15,977,000	$ 35,171,000	$ 29,401,000
Effective tax rate	31.40%	33.10%	31.70%	32.40%
Gross unrecognized tax benefits	19,300,000		19,300,000		18,300,000
Decrease in gross unrecognized tax benefits due to settlements of outstanding audits and the expiration of the statutes of limitation			3,400,000
Long term uncertain tax positions	$ 15,900,000		$ 15,900,000		$ 15,400,000