Consolidated Balance Sheets [Parenthetical] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Balance Sheets Parenthetical [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 1,231	$ 2,685
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	62,645,000	61,852,000
Common stock, shares outstanding	53,098,000	52,830,000
Treasury stock at cost, shares	9,547,000	9,021,000