Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2011	Dec. 31, 2009
Income Taxes [Line Items]
Statutory federal income tax rate	35.00%
Benefit for income taxes	$ 1,584,000	$ 9,082,000	$ 5,831,000
Federal net operating loss carryforward	129,695,000	133,454,000
State net operating loss carryforward	49,551,000	53,350,000
Gross unrecognized tax benefits at end of year	575,000	2,712,000	48,963,000		52,837,000
Increase in additional paid-in-capital from certain tax events	1,600,000	18,400,000
2008 IRS deposits		35,600,000
Benefit received in 2011 from settlement of 2008 IRS deposit				11,100,000
Liability for unrecognized tax benefits	800,000	3,300,000
Expense (benefit) for interest and penalties associated with unrecognized tax benefits	(400,000)	(4,800,000)	(1,800,000)
Interest and penalties component of liability for unrecognized tax benefits	400,000	800,000
Lower bound of reasonably possible decrease to unrecognized tax benefits	0
Upper bound of reasonably possible decrease to unrecognized tax benefits	1,000,000
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforward, expiration dates	2028
State [Member]
Income Taxes [Line Items]
Net operating loss carryforward, expiration dates	2013
Settlements Of State Income Tax Matters [Member] | Operating Loss Carryback [Member]
Income Taxes [Line Items]
Benefit for income taxes	$ 1,600,000	$ 9,100,000	$ 5,800,000