Preferred Stock Offering - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended
	Jun. 30, 2009	Jun. 30, 2012	Dec. 31, 2011
Class of Stock [Line Items]
Preferred stock, shares issued	1,400,000
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Gross proceed from Preferred Stock	$ 140,000
Preferred stock, issuance cost	6,085
Preferred stock, liquidation preference, per share	$ 100
Preferred stock, cumulative dividend rate (in percent)	7.50%
Preferred stock, cumulative dividend rate per share	$ 7.50
Preferred stock, liquidation value		$ 140,438
Common shares issuable per share of convertible preferred stock		14.1844
Preferred stock, conversion price per share		$ 7.05
Common stock issuable upon conversion, shares		19,900,000
Redemption of preferred, term		The Company, at its option, may redeem the preferred stock, in whole or in part, at a price equal to 100% of the liquidation preference, plus all accrued and unpaid dividends.
Percentage of per share price of liquidation preference for redemption		100.00%