CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Operating activities:
Net loss	$ (408.7)	$ (293.3)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, amortization and accretion	104.5	109.7
Stock-based compensation expense	162.5	141.1
Deferred income taxes	(39.6)	221.9
Restructuring charges and other facility exit costs, net	71.5	0.0
Other operating activities	3.4	(10.6)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	393.8	97.4
Prepaid expenses and other current assets	(12.7)	(5.5)
Accounts payable and accrued liabilities	(71.9)	(75.1)
Deferred revenue	15.6	54.5
Accrued income taxes	(64.3)	4.0
Net cash provided by operating activities	154.1	244.1
Investing activities:
Purchases of marketable securities	(1,106.4)	(1,827.9)
Sales of marketable securities	544.7	263.0
Maturities of marketable securities	1,012.6	970.7
Capital expenditures	(65.1)	(41.8)
Acquisitions, net of cash acquired	(85.2)	(104.6)
Other investing activities	(14.8)	(15.5)
Net cash provided by (used in) investing activities	285.8	(756.1)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	102.2	99.3
Taxes paid related to net share settlement of equity awards	(58.9)	(42.3)
Repurchases of common stock	(397.6)	(357.7)
Proceeds from debt, net of discount	0.0	748.3
Other financing activities	0.0	(6.3)
Net cash (used in) provided by financing activities	(354.3)	441.3
Effect of exchange rate changes on cash and cash equivalents	(2.1)	(2.4)
Net increase (decrease) in cash and cash equivalents	83.5	(73.1)
Cash and cash equivalents at beginning of period	1,353.0	1,410.6
Cash and cash equivalents at end of period	$ 1,436.5	$ 1,337.5