CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Jan. 31, 2018	$ 240,545	$ 6	$ 445,318	$ (298)	$ (204,481)
Balance, shares at Jan. 31, 2018		55,712,342
Issuance of common stock for acquisitions	46,157		46,157
Issuance of common stock for acquisitions, shares		262,144
Issuance of common stock for employee share purchase plan	8,778		8,778
Issuance of common stock for employee share purchase plan, shares		505,717
Exercise of stock options	10,448		10,448
Exercise of stock options, shares		2,228,816
Vesting of early exercised stock options	273		273
Stock-based compensation expense	39,139		39,139
Vested restricted stock units, shares		615,282
Impact of the adoption of new accounting pronouncements	5,148				5,148
Other comprehensive income (loss)	(13)			(13)
Net loss	(38,953)				(38,953)
Balance at Oct. 31, 2018	311,522	$ 6	550,113	(311)	(238,286)
Balance, shares at Oct. 31, 2018		59,324,301
Balance at Jul. 31, 2018	252,687	$ 6	481,543	(221)	(228,641)
Balance, shares at Jul. 31, 2018		57,881,483
Issuance of common stock for acquisitions	46,157		46,157
Issuance of common stock for acquisitions, shares		262,992
Issuance of common stock for employee share purchase plan	4,641		4,641
Issuance of common stock for employee share purchase plan, shares		257,034
Exercise of stock options	3,638		3,638
Exercise of stock options, shares		696,205
Vesting of early exercised stock options	91		91
Stock-based compensation expense	14,043		14,043
Vested restricted stock units, shares		226,587
Other comprehensive income (loss)	(90)			(90)
Net loss	(9,645)				(9,645)
Balance at Oct. 31, 2018	311,522	$ 6	550,113	(311)	(238,286)
Balance, shares at Oct. 31, 2018		59,324,301
Balance at Jan. 31, 2019	313,281	$ 6	567,797	335	(254,857)
Balance, shares at Jan. 31, 2019		60,455,381
Equity component of 2025 Notes, net of issuance costs	246,967		246,967
Purchase of capped calls	(118,738)		(118,738)
Cancellation of common stock issued from acquisitions,shares		(7,784)
Issuance of common stock for employee share purchase plan	11,455		11,455
Issuance of common stock for employee share purchase plan, shares		215,412
Exercise of stock options	13,731	$ 1	13,730
Exercise of stock options, shares		2,164,207
Stock-based compensation expense	60,832		60,832
Vested restricted stock units, shares		840,059
Other comprehensive income (loss)	(1,253)			(1,253)
Net loss	(66,779)				(66,779)
Balance at Oct. 31, 2019	459,496	$ 7	782,043	(918)	(321,636)
Balance, shares at Oct. 31, 2019		63,667,275
Balance at Jul. 31, 2019	454,072	$ 7	750,617	(1,233)	(295,319)
Balance, shares at Jul. 31, 2019		62,727,158
Issuance of common stock for employee share purchase plan	6,059		6,059
Issuance of common stock for employee share purchase plan, shares		106,654
Exercise of stock options	3,189		3,189
Exercise of stock options, shares		524,686
Stock-based compensation expense	22,178		22,178
Vested restricted stock units, shares		308,777
Other comprehensive income (loss)	315			315
Net loss	(26,317)				(26,317)
Balance at Oct. 31, 2019	$ 459,496	$ 7	$ 782,043	$ (918)	$ (321,636)
Balance, shares at Oct. 31, 2019		63,667,275