CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Operating activities:
Net loss	$ (393.4)	$ (408.7)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, amortization and accretion	81.5	104.5
Stock-based compensation expense	199.5	162.5
Deferred income taxes	7.3	(39.6)
Restructuring charges and other facility exit costs, net	0.2	71.5
Other operating activities	18.1	3.4
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	143.3	393.8
Prepaid expenses and other current assets	(6.5)	(12.7)
Accounts payable and accrued liabilities	(69.3)	(71.9)
Deferred revenue	(21.8)	15.6
Accrued income taxes	(37.3)	(64.3)
Net cash (used in) provided by operating activities	(78.4)	154.1
Investing activities:
Purchases of marketable securities	(419.6)	(1,106.4)
Sales of marketable securities	199.2	544.7
Maturities of marketable securities	530.1	1,012.6
Capital expenditures	(39.3)	(65.1)
Acquisitions, net of cash acquired	0.0	(85.2)
Other investing activities	(11.5)	(14.8)
Net cash provided by investing activities	258.9	285.8
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	93.2	102.2
Taxes paid related to net share settlement of equity awards	(120.6)	(58.9)
Repurchases of common stock	(437.9)	(397.6)
Proceeds from debt, net of discount	496.9	0.0
Repayment of debt	(400.0)	0.0
Other financing activities	(5.8)	0.0
Net cash used in financing activities	(374.2)	(354.3)
Effect of exchange rate changes on cash and cash equivalents	5.8	(2.1)
Net (decrease) increase in cash and cash equivalents	(187.9)	83.5
Cash and cash equivalents at beginning of period	1,213.1	1,353.0
Cash and cash equivalents at end of period	$ 1,025.2	$ 1,436.5