Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,475	$ 1,624
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0005	$ 0.0005
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	76,509,709	61,631,573
Common stock, shares outstanding	75,284,624	61,279,050
Treasury stock, shares	1,225,085	352,523

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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