Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net loss	$ (53,746)	$ (63,828)	$ (39,714)
Adjustments to reconcile net loss to net cash and cash equivalents provided by operating activities:
Depreciation and amortization	28,793	23,428	15,786
Stock-based compensation	97,754	76,261	47,317
Deferred income tax (benefit) expense	(799)	36	(11,546)
Amortization of debt discount and issuance costs	21,790	20,335	12,366
Accretion of bond discount premium	(14,160)	(6,787)	(1,576)
Non-cash rent expense		2,336	5,039
Unrealized currency translation	(156)	483	(139)
Changes in assets and liabilities, net of acquisition
Accounts receivable	(15,428)	(17,726)	(20,180)
Prepaid expenses and other assets	(3,296)	3,880	(5,588)
Deferred commission expense	(9,666)	(23,900)	(4,004)
Right-of-use assets	22,657
Accounts payable	3,927	3,298	1,100
Accrued expenses and other current liabilities	7,819	11,920	8,195
Lease liabilities	(15,781)
Deferred rent		5,799	3,559
Deferred revenue	49,265	49,316	38,999
Net cash and cash equivalents provided by operating activities	118,973	84,851	49,614
Investing Activities:
Purchases of investments	(1,304,847)	(681,632)	(890,009)
Maturities and sales of investments	1,066,366	644,375	533,660
Purchases of property and equipment	(40,372)	(22,305)	(20,276)
Capitalization of software development costs	(13,474)	(11,168)	(7,071)
Acquisition of a business, net of cash acquired	(23,314)		(9,415)
Purchase of strategic investments	(553)	(500)	(3,500)
Net cash and cash equivalents used in investing activities	(316,194)	(71,230)	(396,611)
Financing Activities:
Proceeds from common stock offering, net of offering costs paid of $365	342,628
Repayment of debt	(333)
Employee taxes paid related to the net share settlement of stock-based awards	(6,247)	(8,033)	(4,419)
Proceeds related to the issuance of common stock under stock plans	23,578	21,555	13,086
Proceeds from issuance of convertible notes, net of issuance costs paid of $10,767			389,233
Purchase of note hedge related to convertible notes			(78,920)
Proceeds from the issuance of warrants related to convertible notes, net of issuance costs paid of $200			58,880
Repayment of finance lease obligations	(284)	(744)	(1,054)
Net cash and cash equivalents provided by financing activities	359,342	12,778	376,806
Effect on exchange rate changes on cash and cash equivalents	(720)	(2,069)	2,790
Net increase in cash, cash equivalents and restricted cash	161,401	24,330	32,599
Cash, cash equivalents and restricted cash, beginning of year	117,114	92,784	60,185
Cash, cash equivalents and restricted cash, end of year	278,515	117,114	92,784
Supplemental cash flow disclosure:
Cash paid for interest	1,014	1,036	762
Cash paid for income taxes	3,090	1,842	855
Right-of-use assets obtained in exchange for operating lease facilities	105,496
Non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	4,606	666	680
Asset retirement obligations	$ 2,014	$ 216	$ 575