Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended	3 Months Ended		9 Months Ended			9 Months Ended
	Sep. 30, 2012	Aug. 06, 2012	Sep. 30, 2012 ATM [Member]	Mar. 01, 2012 ATM [Member] Maximum [Member]	Sep. 30, 2012 Common Stock [Member] ATM [Member]	Mar. 01, 2012 Common Stock [Member] ATM [Member]	Sep. 30, 2012 Convertible Common Stock [Member]	Sep. 30, 2012 Restricted Stock Units Awards [Member]	Sep. 30, 2011 Restricted Stock Units Awards [Member]	Sep. 30, 2012 Restricted Stock Units Awards [Member]	Sep. 30, 2011 Restricted Stock Units Awards [Member]	Sep. 30, 2012 Series F Cumulative Preferred Stock [Member]	Sep. 30, 2012 Series F Preferred Stock [Member]
Class of Stock [Line Items]
Underwritten public offering shares		9,400,000
Underwriting Expenses	$ 127
Proceeds to the company	116,715
Shares of Company Stock Issuable under an At-the-Market Offering				12,500,000
Aggregate gross sale proceeds of common stock under the At-the Market offering						125,000
Issuance of common stock under the At-the-Market offering			1,532,598
Weighted average price of common stock issued under the At-the-Market offering			$ 12.03
Net proceeds from issuance of common stock under the At-the-Market offering			18,063
Sale agent commission					369
Converted Shares of common stock							308,503,000
Conversion of Units to Common Stock							2,710
Restricted stock/unit awards to employees										365,137	292,339
Fair value of restricted stock/unit awards										4,327	3,248
Vesting period of restricted stock/unit awards to employees										3 years
Recognized compensation expense related to restricted stock/unit awards								1,309	1,042	3,707	2,768
Unrecognized compensation expense related to restricted stock/unit awards								5,536		5,536
Weighted average period during which unrecognized compensation expense is expected to be recognized										10 months 28 days
Amount of Share Based Compensation expense Capitalized								$ 19	$ 0	$ 19	$ 0
Minimum fixed coupon rate of preferred stock												2.375%
Number of years of U.S treasury rate one													30 years
Number of years of U.S treasury rate two													10 years
LIBOR rate													3 month LIBOR
New coupon rate of preferred stock												5.065%	5.065%