Consolidated Balance Sheets Parenthetical (USD $)
Dec. 31, 2014
Dec. 31, 2013
Stockholders' equity:    
Preferred stock, par value per share $ 0.01 $ 0.01
Preferred stock, shares authorized 20,000,000 20,000,000
Preferred stock, shares issued 0 0
Preferred stock, shares outstanding 0 0
Common stock, par value per share $ 0.01 $ 0.01
Common stock, shares authorized 300,000,000 300,000,000
Common stock, shares issued 62,957,000 62,331,000
Common stock, shares outstanding 45,400,000 44,774,000
Treasury stock, shares at cost 17,557,000 17,557,000