CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Dividends Declared Per Share of Common Stock	$ 0.30	$ 0.30
7.875% Series A Cumulative Redeemable Preferred Stock
Preferred series dividends declared, per share	$ 0.492	$ 0.492
7.625% Series C Cumulative Redeemable Preferred Stock
Preferred series dividends declared, per share	$ 0.477	$ 0.477
7.50% Series D Cumulative Redeemable Preferred Stock
Preferred series dividends declared, per share	$ 0.469	$ 0.469