Supplemental Statement of Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Supplemental Cash Flow Information [Abstract]
Interest payments	$ 122	$ 86	$ 75
Income taxes paid, net from continuing operations	350	384	365
Treasury common shares issued in connection with share-based incentive awards under equity compensation plans, Non-cash financing activities	47	44	43
Withholding taxes on share-based incentive awards, Non-cash financing activities	36	33	28
Treasury common shares issued in connection with discretionary stock contributions to CA, Inc. Savings Harvest Plan, Non-cash financing activities	23	24	24
Treasury common shares issued in connection with ESPP (Employee Stock Purchase Plan), Non-cash financing activities	$ 5	$ 5	$ 5