Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Operating activities:
Net income (loss)	$ (9,207)	$ 38,759
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	185,108	132,772
Amortization of debt discount and issuance costs	7,717	7,185
Gains from acquisitions of strategic investments	0	(12,864)
Amortization of deferred commissions	106,142	88,514
Expenses related to employee stock plans	251,569	188,919
Changes in assets and liabilities, net of business combinations:
Accounts receivable, net	1,757,507	1,307,312
Deferred commissions	(84,449)	(63,519)
Prepaid expenses and other current assets and other assets	(183,411)	(56,671)
Accounts payable, accrued expenses and other liabilities	(301,242)	(286,228)
Deferred revenue	(500,150)	(293,117)
Net cash provided by operating activities	1,229,584	1,051,062
Investing activities:
Business combinations, net of cash acquired	(19,781)	(1,799)
Strategic investments, net	(458)	(22,061)
Purchases of marketable securities	(698,561)	(589,336)
Sales of marketable securities	103,837	222,934
Maturities of marketable securities	3,850	23,285
Capital expenditures	(156,602)	(83,301)
Net cash used in investing activities	(767,715)	(450,278)
Financing activities:
Proceeds from employee stock plans	159,807	89,141
Principal payments on capital lease obligations	(9,443)	(49,968)
Payments on revolving credit facility	(200,000)	0
Net cash provided by (used in) financing activities	(49,636)	39,173
Effect of exchange rate changes	6,122	763
Net increase in cash and cash equivalents	418,355	640,720
Cash and cash equivalents, beginning of period	1,606,549	1,158,363
Cash and cash equivalents, end of period	2,024,904	1,799,083
Cash paid during the period for:
Interest	6,722	23,750
Income taxes, net of tax refunds	17,347	7,909
Non-cash investing and financing activities:
Fixed assets acquired under capital leases	2,471	585
Building - leased facility acquired under financing obligation	0	1,676
Fair value of equity awards assumed	0	11,449
Fair value of common stock issued as consideration for business combinations	6,193	278,372
Non-cash equity liability (See Note 9)	$ 7,485	$ 0