Recently Issued Accounting Standards ASU Adoption (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended			6 Months Ended
	Jul. 31, 2016	Apr. 30, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Feb. 01, 2016	Jan. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Long-term income taxes payable	$ 42.7	$ 37.3	$ 160.2	$ 42.7	$ 160.2		$ 161.4
Common stock and additional paid-in capital	1,857.1	1,867.2		1,857.1			1,821.5
Retained earnings	(395.6)	(193.3)	131.3	(395.6)	131.3		$ (80.8)
Cost of subscription revenue	38.2	39.8	40.0	78.0	78.7
Cost of license and other revenue	46.9	52.6	53.0	99.5	106.1
Gross profit	465.6	419.5	516.5	885.1	1,071.2
Marketing and sales	243.1	240.8	240.8	483.9	494.7
Research and development	193.0	193.5	193.1	386.5	387.6
General and administrative	68.6	74.7	70.1	143.3	146.0
(Loss) from operations	(62.9)	(149.7)	4.3	(212.6)	25.8
Provision for income taxes	25.2	(14.4)	269.5	39.6	272.2
Net (loss)	$ (98.2)	$ (167.7)	(268.6)	$ (265.9)	(249.5)
Basic and diluted weighted average shares outstanding (in shares)		224.4
Basic and diluted net (loss) per share (in dollars per share)		$ (0.75)
Scenario, Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Long-term income taxes payable		$ 153.8	124.0		124.0
Common stock and additional paid-in capital		1,865.6
Retained earnings		(308.2)	164.4		164.4
Cost of subscription revenue		39.7
Cost of license and other revenue		52.8
Gross profit		419.4
Marketing and sales		242.9
Research and development		195.5
General and administrative		75.8
(Loss) from operations		(155.0)
Provision for income taxes		(14.4)	236.4		239.1
Net (loss)		$ (173.0)	(235.5)		(216.4)
Basic and diluted weighted average shares outstanding (in shares)		224.4
Basic and diluted net (loss) per share (in dollars per share)		$ (0.77)
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Long-term income taxes payable			36.2		36.2
Retained earnings			(33.1)		(33.1)
Provision for income taxes			33.1		33.1
Net (loss)			$ (33.1)		$ (33.1)
Accounting Standards Update 2016-09 | New Accounting Pronouncement, Early Adoption, Effect
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Liability for uncertain tax positions, noncurrent						$ 116.5
Cumulative effect of new accounting pronouncement						6.9
Accounting Standards Update 2016-09 | Restatement Adjustment | New Accounting Pronouncement, Early Adoption, Effect
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Long-term income taxes payable		$ 0.0				(116.5)
Common stock and additional paid-in capital		(5.3)				6.9
Retained earnings		5.3				109.6
Cost of subscription revenue		0.1
Cost of license and other revenue		(0.2)
Gross profit		0.1
Marketing and sales		(2.1)
Research and development		(2.0)
General and administrative		(1.1)
(Loss) from operations		5.3
Provision for income taxes		0.0
Net (loss)		$ 5.3
Basic and diluted weighted average shares outstanding (in shares)		0.0
Basic and diluted net (loss) per share (in dollars per share)		$ 0.02
Accounting Standards Update 2016-09 | Retained Earnings | New Accounting Pronouncement, Early Adoption, Effect
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of new accounting pronouncement						$ 116.5