Preferred Stock Offering - Additional Information (Detail) (USD $)	1 Months Ended		9 Months Ended			1 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended
	Aug. 29, 2012	Jun. 30, 2009	Sep. 30, 2012	Aug. 31, 2012	Dec. 31, 2011	Aug. 31, 2012 Preferred Stock	Sep. 30, 2012 Preferred Stock	Aug. 31, 2012 Common Stock	Sep. 30, 2012 Common Stock	Aug. 31, 2012 Exchanged for Preferred Stock	Aug. 29, 2012 Exchanged for Preferred Stock
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		$ 140,000,000
Preferred stock, issuance cost		6,085,000
Preferred stock, cumulative dividend rate (in percent)	7.50%	7.50%	7.50%
Preferred stock to debt and common stock exchange (in shares)						982,361
Preferred stock to common stock exchange							(350,000)	5,866,821	5,867,000
Convertible senior notes	112,500,000									63,227,000	63,227,000
Preferred stock, shares outstanding			417,639	417,639	1,400,000
Initial conversion rate, number of common stock issuable			133.3333				14.1844
Conversion price per share			$ 7.50				$ 7.05
Common stock issuable upon conversion, shares							5,924,000
Preferred stock, liquidation preference, per share			$ 100
Preferred stock, cumulative dividend rate per share			$ 7.50
Preferred stock, liquidation preference, value			$ 41,894,000
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%