CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (12,661)	$ (17,100)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Stock-based compensation expense	7,573	10,290
Depreciation	863	932
Changes in operating assets and liabilities:
Accounts receivable	21,121	22,821
Deferred commissions	937	(35)
Other current and noncurrent assets	(398)	(2,647)
Accounts payable	(101)	186
Unearned revenue	(4,172)	(2,958)
Customer arrangements with termination rights	(2,667)	(2,184)
Accrued expenses and other long-term liabilities	(3,328)	(1,489)
Net cash provided by operating activities	7,167	7,816
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(93)	(177)
Proceeds from maturities of investment securities		1,000
Purchase of investment securities		(546)
Net cash provided by (used in) investing activities	(93)	277
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Employee Stock Purchase Plan	837	953
Taxes paid for net settlement of equity awards	(3,182)	(4,409)
Proceeds from exercise of stock options	123	798
Repurchase of common stock	(684)	(3,601)
Net cash provided by (used in) financing activities	(2,906)	(6,259)
NET CHANGE IN CASH AND CASH EQUIVALENTS	4,168	1,834
CASH AND CASH EQUIVALENTS—Beginning of period	94,415	104,613
CASH AND CASH EQUIVALENTS—End of period	98,583	106,447
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	621	269
Lease payments for amounts included in the measurement of lease liabilities	1,696	1,832
SUPPLEMENTAL DISCLOSURES OF NONCASH FINANCING ACTIVITIES:
Value of shares issued under Bonus Plans	4,765	6,374
Value of shares issued under the Employee Stock Purchase Plan	2,151	2,047
Unpaid property and equipment purchases	$ 32	$ 165