Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Commitments and Contingencies Disclosure [Line Items]
Selling & administrative	$ 8,218,000	$ 6,275,000	$ 24,536,000	$ 21,381,000
Operating income (loss)	10,456,000	10,981,000	30,805,000	28,888,000
Legal Fees and Other Third Party Costs
Commitments and Contingencies Disclosure [Line Items]
Selling & administrative	1,100,000	600,000	3,400,000	2,500,000
Legal Fees and Other Third Party Costs | Directors and Officers Liability Insurance
Commitments and Contingencies Disclosure [Line Items]
Reimbursement from insurance carrier	1,000,000	1,500,000	3,000,000	3,300,000
Operating income (loss)	$ (100,000)	$ 900,000	$ (400,000)	$ 800,000
Legal Fees and Other Third Party Costs | Directors and Officers Liability Insurance | Minimum
Commitments and Contingencies Disclosure [Line Items]
Expenses that are subject to insurance reimbursement, collection period	90
Legal Fees and Other Third Party Costs | Directors and Officers Liability Insurance | Maximum
Commitments and Contingencies Disclosure [Line Items]
Expenses that are subject to insurance reimbursement, collection period	120