Components of Income Before Income Tax Expense and Reconciliation of Statutory Federal Income Tax Rate to Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income (loss) before income tax expense:
U.S.	$ 99,652	$ 89,188	$ 70,657
International	(4,705)	(841)	1,115
Income (loss) before income tax expense	94,947	88,347	71,772
Income tax expense (benefit):
Current, U.S.	35,768	32,871	18,706
Current, State, local and foreign	5,039	3,892	2,441
Current, Total	40,807	36,763	21,147
Deferred income tax expense (benefit):
Deferred, U.S.	(3,925)	(3,783)	3,700
Deferred, State, local and foreign	1,134	2,076	2,447
Deferred, Total	(2,791)	(1,707)	6,147
Income tax expense (benefit)	38,016	35,056	27,294
U.S. statutory rate	35.00%	35.00%	35.00%
Income tax expense at U.S. statutory rate	33,231	30,921	25,120
State income taxes, net of federal benefit	4,101	3,452	2,834
Meals and entertainment	234	198	187
Change in valuation allowance for foreign tax credit and capital loss	(340)	1,099	(169)
Nondeductible capitalized acquisition costs	1,491
Domestic production activities deduction	(568)	(525)	(508)
Other	(133)	(89)	(170)
Income tax expense (benefit)	$ 38,016	$ 35,056	$ 27,294
Effective tax rate	40.00%	39.70%	38.00%