CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended			12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017		Jul. 31, 2018	Jul. 31, 2017		Jan. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (38,085)	$ (39,285)		$ (74,722)	$ (79,371)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	11,849	9,765		23,244	19,337
Stock-based compensation expense	30,683	24,067		57,296	47,013
Amortization of deferred commissions	4,040	5,368		7,715	10,358
Other	26	19		5	41
Changes in operating assets and liabilities:
Accounts receivable, net	(23,754)	(25,124)		47,936	12,222
Deferred commissions	(8,588)	(5,835)		(13,304)	(8,619)
Prepaid expenses and other assets	267	(3,402)	[1]	(4,933)	(5,943)	[1]
Accounts payable	(1,680)	(121)		(1,205)	7,061
Accrued expenses and other liabilities	9,113	7,074		(15,604)	(3,893)
Deferred rent	294	1,189		337	1,719
Deferred revenue	14,568	16,524		(9,592)	(1,145)
Net cash (used in) provided by operating activities	(1,267)	(9,761)	[1]	17,173	(1,220)	[1]
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,326)	(1,013)		(7,366)	(1,797)
Proceeds from sale of property and equipment		2		1	29
Acquisitions	(458)			(458)
Net cash used in investing activities	(3,784)	(1,011)		(7,823)	(1,768)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	9,469	2,957		12,831	5,413
Proceeds from issuances of common stock under employee stock purchase plan				11,846	8,881
Employee payroll taxes paid related to net share settlement of restricted stock units	(12,010)	(5,821)		(25,305)	(14,935)
Acquisition related contingent consideration		(991)			(991)
Payments of capital lease obligations	(5,752)	(4,176)		(12,902)	(7,912)
Net cash used in financing activities	(8,293)	(8,031)		(13,530)	(9,544)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(158)	149		(282)	178
Net decrease in cash, cash equivalents, and restricted cash	(13,502)	(18,654)	[1]	(4,462)	(12,354)	[1]
Cash, cash equivalents, and restricted cash, beginning of period	217,466	210,472		208,426	204,172		$ 204,172
Cash, cash equivalents, and restricted cash, end of period	203,964	191,818		203,964	191,818		208,426
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest, net of amounts capitalized	587	466		1,172	889
Cash paid for income taxes, net of tax refunds	131	188		992	733
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Change in accrued equipment purchases	391	2,054		(2,177)	890
Purchases of property and equipment under capital lease	8,465	5,972		18,521	15,681
Change in unpaid tax related to capital lease	150	200		235	435
Issuance of common stock in connection with acquisitions	1,053			1,053
Contingent consideration accruals in connection with acquisitions	936			936
Timing of settlement of stock options exercise	(1,007)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH INFORMATION:
Cash and cash equivalents, beginning of period	217,116	183,691		208,076	177,391		177,391
Restricted cash, beginning of period	350	26,781		350	26,781		26,781
Cash, cash equivalents, and restricted cash, beginning of period	217,466	210,472		208,426	204,172		204,172
Cash and cash equivalents, end of period	203,726	165,275		203,726	165,275		208,076
Restricted cash, end of period	238	26,543		238	26,543		350
Cash, cash equivalents, and restricted cash, end of period	$ 203,964	$ 191,818		$ 203,964	$ 191,818		$ 208,426

[1] Adjusted due to the adoption of ASU 2016-18