Equity - Schedule of Stock Redeemed and Retired (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
8.05% Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Shares redeemed and retired		0		2,740,874
Redemption and Repurchase Costs		$ 0	[1]	$ 69,459	[1]
Deemed dividend	0	0	[2]	2,346	[2]
6.50% Series C Cumulative Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Shares redeemed and retired		0		34,800
Redemption and Repurchase Costs		0		1,462
Discount (Deemed negative dividend)	0	0	[2]	(229)	[2]
7.55% Series D Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Shares redeemed and retired		6,200,000		0
Redemption and Repurchase Costs		155,621	[1]	0	[1]
Deemed dividend	$ 0	$ 5,230	[2]	$ 0	[2]

[1] Includes accrued and unpaid dividends.

[2] Represents the difference between the redemption/repurchase cost and historical GAAP cost. Accordingly, net income (loss) was adjusted for the deemed dividends/deemed negative dividends to arrive at net income (loss) attributable to common shareholders.