Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Preferred Stock, Par or Stated Value Per Share (usd per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	9,945,539	9,945,539
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share (usd per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	85,594,060	84,253,065
Common Stock, Shares, Outstanding	84,594,060	84,253,065
6.75% Series C Cumulative Redeemable Perpetual Preferred Stock
Preferred Stock, Par or Stated Value Per Share (usd per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	54,461	54,461
Preferred Stock, Shares Issued	54,458	54,458
Preferred Stock, Shares Outstanding	54,458	54,458
Cumulative Series D 6% Non-Qualified Preferred Stock
Preferred Stock, Par or Stated Value Per Share (usd per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	0	0
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0