Stock-Based Compensation and Earnings Per Share - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended			6 Months Ended
	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011
Compensating Balances [Line Items]
Accelerated vesting of restricted shares	300,000
Accelerated stock compensation expense	$ 6,200,000
Common stock purchased by employees through payroll deductions, discount				15.00%
Stock-based compensation expenses		510,000	(87,000)		1,002,000	8,383,000
Issuances of common stock to Chief Executive office in lieu of cash bonus, shares		29,835			36,023
2009 Equity Incentive Plan
Compensating Balances [Line Items]
Number of share authorized		2,000,000			2,000,000
Shares available for future issuance		1,500,000			1,500,000
Service-Based Restricted Stock Units
Compensating Balances [Line Items]
Unrecognized compensation cost related to non-vested restricted stock		100,000			100,000
Stock option compensation recognition period (in years)					4 years
Market Condition Restricted Stock Units
Compensating Balances [Line Items]
Performance period (in years)					3 years
Stock-based compensation expenses		$ 500,000			$ 600,000