Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued	6,000,000	0	0
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000	210,000,000
Common stock, shares issued	61,632,464	61,479,189	61,372,763
Treasury stock, shares	1,662,927
Series A Preferred Stock [Member]
Liquidation preference value	$ 25