Supplemental Statement of Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Interest payments	$ 86	$ 75	$ 75
Income taxes paid, net from continuing operations	384	365	411
Excess tax benefits from share-based incentive awards included in financing activities from continuing operations	5	4	3
Share-based incentive awards issued under equity compensation plans, Non-cash financing activities	44	43	44
Withholding taxes on share-based incentive awards, Non-cash financing activities	33	28	28
Discretionary stock contributions to CA, Inc. Savings Harvest Plan, Non-cash financing activities	24	24	26
Treasury common shares issued in connection with Employee Stock Purchase Plan, Non-cash financing activities	$ 5	$ 5	$ 5