CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000	300,000,000
Common stock, shares issued	37,068,904	37,068,904	37,068,904
Treasury stock, shares	13,749,764	10,969,425	10,045,948