CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES:
Net loss	$ (18,567)	$ (14,519)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Stock-based compensation expense	10,338	6,103
Depreciation	10,343	9,017
Amortization of purchased intangibles	2,131	3,968
Amortization of tenant allowance	(204)	(125)
Deferred income taxes	179	823
Provision for doubtful accounts, net	1,326	1,363
Changes in operating assets and liabilities:
Accounts receivable	(15,127)	(1,719)
Prepaid expenses and other current assets	(11,370)	(2,248)
Other assets	(218)	75
Accounts payable	571	(4,352)
Accrued expenses and other current liabilities	(8,849)	(2,954)
Deferred revenue	22,381	8,549
Other liabilities	(42)	(463)
Net cash (used in) provided by operating activities	(7,108)	3,518
INVESTING ACTIVITIES:
Purchases of property and equipment, including capitalized software	(13,832)	(12,176)
Cash held as collateral for foreign exchange forward contracts	1,451	2,511
Payments for acquisitions and intangible assets, net of cash acquired	(1,502)	(345)
Net cash used in investing activities	(13,883)	(10,010)
FINANCING ACTIVITIES:
Proceeds from issuance of common stock in connection with the exercise of options	32,712	7,748
Repurchase of common stock	(1,345)	(1,741)
Net cash provided by financing activities	31,367	6,007
EFFECT OF FOREIGN EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(140)	3,957
CHANGE IN CASH AND CASH EQUIVALENTS	10,236	3,472
CASH AND CASH EQUIVALENTS - Beginning of the period	56,115	50,889
CASH AND CASH EQUIVALENTS - End of the period	66,351	54,361
SUPPLEMENTAL DISCLOSURE OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	5,524	540
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchase of property and equipment recorded in accounts payable	550	507
Leasehold improvements funded by landlord	1,449	0
Contingent earn-out in connection with the acquisition of Conversable recorded in accrued expenses and common stock	2,124	0
BotCentral
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Issuance of shares of common stock in connection with acquisition	1,000	0
Conversable, Inc.
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Issuance of shares of common stock in connection with acquisition	$ 3,000	$ 0