Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES:
Net loss	$ (124,974)	$ (107,594)	$ (96,071)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Stock-based compensation expense	69,656	65,946	44,105
Depreciation	27,423	22,826	16,366
Loss on disposal	0	5,147	0
Amortization of tenant allowance	0	0	(516)
Amortization of purchased intangibles	5,609	2,780	2,932
Amortization of finance leases	3,718	772	0
Amortization of debt issuance costs	2,499	1,340	956
Accretion of debt discount on convertible senior notes	33,309	11,564	7,605
Change in fair value of contingent consideration	0	(263)	(328)
Allowance for credit losses	4,879	3,211	2,159
Gain on settlement of leases	(3,483)	0	0
Deferred income taxes	(6,239)	579	(1,207)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(17,309)	6,371	(43,757)
Prepaid expenses and other current assets	(3,178)	23	(4,712)
Contract acquisition costs noncurrent	(1,876)	(6,463)	(13,718)
Other assets	547	(37)	(30)
Accounts payable	801	(733)	3,808
Accrued expenses and other current liabilities	8,626	22,931	(10,882)
Deferred revenue	7,774	(3,118)	33,953
Operating lease liabilities	(4,590)	8,276	388
Other liabilities	55	47	(209)
Net cash provided by (used in) operating activities	3,247	33,605	(59,158)
INVESTING ACTIVITIES:
Purchases of property and equipment, including capitalized software	(45,703)	(41,641)	(47,582)
Payments for acquisitions, net of cash acquired	(70,759)	0	0
Purchases of intangible assets	(2,610)	(1,835)	(924)
Repayment of debt acquired in acquisition	(21,177)	0	0
Net cash used in investing activities	(140,249)	(43,476)	(48,506)
FINANCING ACTIVITIES:
Principal payments for financing leases	(3,554)	(1,154)	0
Repurchase of common stock	(709)	0	(903)
Proceeds from issuance of common stock in connection with the exercise of options and ESPP	16,110	25,355	21,060
Proceeds from issuance of convertible senior notes	(4)	517,500	230,000
Payment of issuance costs in connection with convertible senior notes	0	(11,800)	(8,635)
Payment related to contingent consideration	0	0	(487)
Purchase of capped call option	0	(46,058)	(23,184)
Net cash provided by financing activities	11,843	483,843	217,851
Effect of foreign exchange rate changes on cash and cash equivalents	(5,461)	3,657	(113)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(130,620)	477,629	110,074
Cash, cash equivalents, and restricted cash - beginning of year	654,152	176,523	66,449
Cash, cash equivalents, and restricted cash - end of year	523,532	654,152	176,523
Reconciliation of cash, cash equivalents, and restricted cash to consolidated balance sheets
Cash and cash equivalents	521,846	654,152	176,523
Restricted cash in prepaid expenses and other current assets	1,686	0	0
Total cash, cash equivalents, and restricted cash	523,532	654,152	176,523
Supplemental disclosure of other cash flow information:
Cash paid for income taxes	582	4,651	3,304
Cash paid for interest	2,090	1,931	848
Supplemental disclosure of non-cash investing and financing activities:
Purchase of property and equipment recorded in accounts payable	470	1,638	1,198
ROU assets obtained in exchange for operating lease liabilities	2,125	0	21,588
ROU assets obtained in exchange for finance lease liabilities	0	10,818	0
Issuance of shares of common stock as earn-out payment in connection with AdvantageTec Inc.		293
Issuance of shares of common stock to settle cash awards	$ 33,503	$ 24,657	0
Issuance of shares of common stock to settle cash awards (in shares)	400,700	991,905
Conversable Dec 13 2019
Supplemental disclosure of non-cash investing and financing activities:
Issuance of shares of common stock in connection with acquisition	$ 0	$ 0	$ 1,000
Issuance of shares of common stock in connection with acquisition (in shares)			38,462
AdvantageTec
Supplemental disclosure of non-cash investing and financing activities:
Issuance of shares of common stock as earn-out payment in connection with AdvantageTec Inc.	0	$ 293	$ 0
Issuance of shares of common stock as earn-out payment in connection with AdvantageTec Inc. (in shares)		11,508
e-bot7
Supplemental disclosure of non-cash investing and financing activities:
Issuance of shares of common stock in connection with acquisition	$ 20,012	$ 0	0
Issuance of shares of common stock in connection with acquisition (in shares)	351,462
Fair value of contingent earn-out recorded in other long-term liabilities	$ 6,170	0	0
Tenfold
Supplemental disclosure of non-cash investing and financing activities:
Issuance of shares of common stock in connection with acquisition	$ 41,224	0	0
Issuance of shares of common stock in connection with acquisition (in shares)	698,219
Fair value of contingent earn-out recorded in other long-term liabilities	$ 6,946	0	0
VoiceBase
Supplemental disclosure of non-cash investing and financing activities:
Issuance of shares of common stock in connection with acquisition	$ 67,557	0	0
Issuance of shares of common stock in connection with acquisition (in shares)	1,080,532
Fair value of contingent earn-out recorded in other long-term liabilities	$ 16,714	$ 0	$ 0