CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Shares Outstanding	0	0
Current assets
Allowance for doubtful accounts	$ 2,887	$ 2,888
Accumulated amortization	$ 1,163	$ 761
Stockholders' equity
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	240,000,000	240,000,000
Common stock, shares issued	80,717,000	77,366,000
Common stock, shares outstanding	52,622,000	54,142,000
Treasury stock, shares	28,095,000	23,224,000