Impact of Adopting Topic 606 3 (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Total revenue	$ 895	$ 1,034	$ 1,833	$ 2,059
Expenses:
Amortization of capitalized software costs	49	67	109	137
Selling and marketing	252	244	487	490
General and administrative	99	97	203	204
Product development and enhancements	158	161	320	319
Depreciation and amortization of other intangible assets	28	27	54	53
Other expenses, net	4	9	107	20
Total expenses before interest and income taxes	728	752	1,564	1,514
Income before interest and income taxes	167	282	269	545
Interest expense, net	19	24	39	49
Income before income taxes	148	258	230	496
Income tax expense (benefit)	19	74	(65)	134
Net income	$ 129	$ 184	$ 295	$ 362
Basic income per common share:
Basic income per common share (in dollars per share)	$ 0.31	$ 0.44	$ 0.70	$ 0.86
Basic weighted average shares used in computation	413	415	414	415
Diluted income per common share:
Diluted income per common share (in dollars per share)	$ 0.31	$ 0.44	$ 0.70	$ 0.86
Diluted weighted average shares used in computation	416	416	416	416
License and Maintenance
Revenue:
Total revenue	$ 824	$ 959	$ 1,694	$ 1,909
Expenses:
Costs of licensing and maintenance and professional services	74	73	150	144
Professional Services
Revenue:
Total revenue	71	75	139	150
Expenses:
Costs of licensing and maintenance and professional services	64	74	134	147
As Reported under Topic 606
Revenue:
Total revenue	895		1,833
Expenses:
Amortization of capitalized software costs	49		109
Selling and marketing	252		487
General and administrative	99		203
Product development and enhancements	158		320
Depreciation and amortization of other intangible assets	28		54
Other expenses, net	4		107
Total expenses before interest and income taxes	728		1,564
Income before interest and income taxes	167		269
Interest expense, net	19		39
Income before income taxes	148		230
Income tax expense (benefit)	19		(65)
Net income	$ 129		$ 295
Basic income per common share:
Basic income per common share (in dollars per share)	$ 0.31		$ 0.70
Basic weighted average shares used in computation	413		414
Diluted income per common share:
Diluted income per common share (in dollars per share)	$ 0.31		$ 0.70
Diluted weighted average shares used in computation	416		416
As Reported under Topic 606 | License and Maintenance
Revenue:
Total revenue	$ 824		$ 1,694
Expenses:
Costs of licensing and maintenance and professional services	74		150
As Reported under Topic 606 | Professional Services
Revenue:
Total revenue	71		139
Expenses:
Costs of licensing and maintenance and professional services	64		134
Proforma as if the previous accounting of Topic 605 was in effect
Revenue:
Total revenue	1,045	1,034	2,097	2,059
Expenses:
Amortization of capitalized software costs	49		109
Selling and marketing	246		471
General and administrative	99		202
Product development and enhancements	158		320
Depreciation and amortization of other intangible assets	28		54
Other expenses, net	4		112
Total expenses before interest and income taxes	728		1,561
Income before interest and income taxes	317		536
Interest expense, net	19		39
Income before income taxes	298		497
Income tax expense (benefit)	53		(9)
Net income	$ 245		$ 506
Basic income per common share:
Basic income per common share (in dollars per share)	$ 0.59		$ 1.21
Basic weighted average shares used in computation	413		414
Diluted income per common share:
Diluted income per common share (in dollars per share)	$ 0.58		$ 1.20
Diluted weighted average shares used in computation	416		416
Proforma as if the previous accounting of Topic 605 was in effect | License and Maintenance
Revenue:
Total revenue	$ 971		$ 1,949
Expenses:
Costs of licensing and maintenance and professional services	74		150
Proforma as if the previous accounting of Topic 605 was in effect | Professional Services
Revenue:
Total revenue	74	$ 75	148	$ 150
Expenses:
Costs of licensing and maintenance and professional services	70		143
Effect of Change Higher/(Lower)
Revenue:
Total revenue	(150)		(264)
Expenses:
Amortization of capitalized software costs	0		0
Selling and marketing	6		16
General and administrative	0		1
Product development and enhancements	0		0
Depreciation and amortization of other intangible assets	0		0
Other expenses, net	0		(5)
Total expenses before interest and income taxes	0		3
Income before interest and income taxes	(150)		(267)
Interest expense, net	0		0
Income before income taxes	(150)		(267)
Income tax expense (benefit)	(34)		(56)
Net income	$ (116)		$ (211)
Basic income per common share:
Basic income per common share (in dollars per share)	$ (0.28)		$ (0.51)
Basic weighted average shares used in computation	0		0
Diluted income per common share:
Diluted income per common share (in dollars per share)	$ (0.27)		$ (0.50)
Diluted weighted average shares used in computation	0		0
Effect of Change Higher/(Lower) | License and Maintenance
Revenue:
Total revenue	$ (147)		$ (255)
Expenses:
Costs of licensing and maintenance and professional services	0		0
Effect of Change Higher/(Lower) | Professional Services
Revenue:
Total revenue	(3)		(9)
Expenses:
Costs of licensing and maintenance and professional services	$ (6)		$ (9)