Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (196,336)	$ (152,607)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	66,785	51,381
Amortization of debt discount and debt issuance costs	20,186	14,414
Stock-based compensation expense	174,790	155,938
Other	(483)	(5,037)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable, net	17,079	(62,623)
Inventory	2,722	(17,103)
Deferred commissions	(8,158)	(9,127)
Prepaid expenses and other assets	1,464	1,996
Operating lease right-of-use assets	19,962
Accounts payable	(35,244)	11,800
Accrued compensation and other liabilities	(31,011)	7,592
Operating lease liabilities	(19,020)
Deferred revenue	106,980	87,005
Net cash provided by operating activities	119,716	83,629
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(74,206)	(70,807)
Acquisitions, net of cash acquired	(51,594)	(13,899)
Purchase of intangible assets	(9,000)	0
Purchases of marketable securities	(640,024)	(558,248)
Sales of marketable securities	116,518	18,802
Maturities of marketable securities	345,657	156,049
Net cash used in investing activities	(312,649)	(468,103)
CASH FLOWS FROM FINANCING ACTIVITIES
Net proceeds from exercise of stock options	25,804	43,342
Proceeds from issuance of common stock under employee stock purchase plan	43,291	33,444
Proceeds from issuance of convertible senior notes, net of issuance costs	0	562,062
Payment for purchase of capped calls	0	(64,630)
Repayment of debt assumed from acquisitions	(11,555)	(6,101)
Tax withholding on vesting of restricted stock	(8,787)	0
Repurchase of common stock	0	(20,000)
Net cash provided by financing activities	48,753	548,117
Net increase (decrease) in cash, cash equivalents and restricted cash	(144,180)	163,643
Cash, cash equivalents and restricted cash, beginning of period	463,813	258,820
Cash, cash equivalents and restricted cash, end of period	319,633	422,463
CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD:
Cash, cash equivalents and restricted cash, end of period	319,633	422,463
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	3,398	4,121
Cash paid for interest	718	371
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION
Property and equipment purchased but not yet paid	5,202	14,605
Acquisition consideration held back to satisfy potential indemnification claims	0	3,725
Vesting of early exercised stock options	$ 0	$ 320