Stock-Based Compensation and Earnings Per Share - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Compensating Balances [Line Items]
Accelerated vesting of restricted shares	300,000
Accelerated stock compensation expense	$ 6,200,000
Stock-based compensation expenses		(6,000)	225,000	996,000	8,609,000
Director Fees
Compensating Balances [Line Items]
Issuances of common stock in lieu of cash bonus, shares				29,835
Chief Executive Officer
Compensating Balances [Line Items]
Issuances of common stock in lieu of cash bonus, shares				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
Market Condition Restricted Stock Units
Compensating Balances [Line Items]
Performance period (in years)				3 years
Stock-based compensation expenses				600,000
Market Condition Restricted Stock Units | Director Fees
Compensating Balances [Line Items]
Stock-based compensation expenses				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