Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Condensed Consolidated Balance Sheets
Preferred stock, shares authorized	500,000	500,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares	120,000,000	120,000,000
Common stock, shares issued	39,304,294	39,328,503
Common stock, shares outstanding	39,304,294	39,328,503