CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES:
Net loss	$ (3,203)	$ (5,676)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,438	1,913
Depreciation	3,358	2,793
Amortization of purchased intangibles	711	1,431
Amortization of tenant allowance	(42)	(42)
Deferred income taxes	16	(21)
Provision for doubtful accounts, net	496	451
Changes in operating assets and liabilities:
Accounts receivable	(8,467)	2,686
Prepaid expenses and other current assets	(5,841)	(2,548)
Other assets	(21)	0
Accounts payable	(172)	(1,117)
Accrued expenses and other current liabilities	(9,782)	(8,998)
Deferred revenue	19,921	5,942
Other liabilities	(89)	84
Net cash used in operating activities	(677)	(3,102)
INVESTING ACTIVITIES:
Purchases of property and equipment, including capitalized software	(4,595)	(2,729)
Cash held as collateral for foreign exchange forward contracts	1,235	(17)
Payments for acquisitions and intangible assets, net of cash acquired	(263)	(98)
Net cash used in investing activities	(3,623)	(2,844)
FINANCING ACTIVITIES:
Proceeds from issuance of common stock in connection with the exercise of options	5,949	460
Repurchase of common stock	(1,345)	(976)
Net cash provided by (used in) financing activities	4,604	(516)
EFFECT OF FOREIGN EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	1,061	3,332
CHANGE IN CASH AND CASH EQUIVALENTS	1,365	(3,130)
CASH AND CASH EQUIVALENTS - Beginning of the period	56,115	50,889
CASH AND CASH EQUIVALENTS - End of the period	57,480	47,759
SUPPLEMENTAL DISCLOSURE OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	553	0
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchase of property and equipment recorded in accounts payable	292	682
Noncash or Part Noncash Acquisition, Costs	$ 1,000	$ 0