Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,611,879	50,611,879
Common stock, shares outstanding	50,611,879	50,611,879
Common stock, treasury shares	4,002,070	4,002,070