Consolidated Balance Sheets [Parenthetical] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Balance Sheets Parenthetical [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 2,622	$ 1,231
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	63,391,000	62,645,000
Common stock, shares outstanding	54,088,000	53,098,000
Treasury stock at cost, shares	9,303,000	9,547,000