Stockholders' Equity (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		3 Months Ended
	Mar. 31, 2012	Mar. 01, 2012 Maximum [Member]	Mar. 31, 2012 Series F Preferred Stock [Member]	Mar. 31, 2012 Series F Cumulative Preferred Stock [Member]	Mar. 31, 2012 Convertible Common Stock [Member]	Mar. 31, 2012 Restricted Unit Awards [Member] Y	Mar. 31, 2011 Restricted Unit Awards [Member]	Mar. 31, 2012 ATM [Member]	Mar. 31, 2012 ATM [Member] Common Stock [Member]	Mar. 01, 2012 ATM [Member] Common Stock [Member]
Stockholders' Equity (Textual) [Abstract]
Shares of Company Stock Issuable under an At-the-Market Offering		12,500,000
Aggregate gross sale proceeds										$ 125,000
Issuance of company common stock								1,532,598
Weighted average price of common stock								$ 12.03
Proceeds from Common Stock Issuance ATM or DRIP								18,063
Sale agent commission									369
Converted Shares of common stock					11,159
Operating Partnership Units resulted in reclassification					99
Restricted common stock/unit awards to employees						365,137	292,339
Fair value of restricted common stock						4,327	3,248
Vesting period of stock awards granted to employees, maximum						P3Y
Recognized compensation related to restricted stock awards						1,099	645
Unrecognized compensation related to unvested restricted stock awards						$ 8,307
Weighted average period during which unrecognized compensation is expected to be recognized						1.05
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
New coupon rate of preferred stock			5.415%	5.415%
LIBOR rate			3 month LIBOR