Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Current portion of deferred revenue	$ 17,149	$ 15,554
Long-term portion of deferred revenue	54,042	54,210
Long-term debt, less current portion	$ 214,010	$ 211,235
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	160,615,416	160,020,466
Common stock, shares outstanding	160,615,416	160,020,466
Related Parties, Aggregated
Related Party Transaction [Line Items]
Current portion of deferred revenue	$ 8,024	$ 6,945
Long-term portion of deferred revenue	50,620	52,227
Long-term debt, less current portion	$ 55,515	$ 55,290

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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