Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (22,182)	$ (29,032)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	3,237	3,419
Stock-based compensation expense	9,450	9,160
Provision for doubtful accounts	478	394
Foreign currency re-measurement gain	(238)	(119)
Other non-cash expenses	175	130
Changes in assets and liabilities:
Accounts receivable	1,240	4,945
Prepaid expenses and other assets	412	(1,401)
Accounts payable	(1,657)	1,904
Accrued expenses	(2,122)	(3,462)
Deferred revenue	11,366	14,405
Other liabilities	(819)	(72)
Net cash (used in) provided by operating activities	(660)	271
Cash flows from investing activities:
Purchases of property and equipment	(2,578)	(1,842)
Capitalization of internal-use software costs	(316)	0
Purchases of investments	(15,828)	0
Sale and maturities of investments	14,605	0
Net cash used in investing activities	(4,117)	(1,842)
Cash flows from financing activities:
Deferred business acquisition payment	(796)	0
Payments of capital lease obligations	0	(68)
Taxes paid related to net share settlement of equity awards	(261)	(3,760)
Proceeds from employee stock purchase plan	1,499	2,096
Proceeds from stock option exercises	4,111	1,431
Net cash provided by (used in) financing activities	4,553	(301)
Effect of exchange rate changes on cash and cash equivalents	144	74
Net increase (decrease) in cash and cash equivalents	(80)	(1,798)
Cash and cash equivalents, beginning of period	53,148	86,553
Cash and cash equivalents, end of period	53,068	84,755
Supplemental cash flow information:
Cash paid for income taxes	623	334
Cash paid for interest	$ 0	$ 1