Supplemental Statement of Cash Flows Information 2 (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Information [Abstract]
Interest payments	$ 24	$ 23
Income taxes paid, net	47	62
Share-based incentive awards issued under equity compensation plans, Non-cash financing activities	45	42
Withholding taxes on share-based incentive awards, Non-cash financing activities	34	31
Discretionary stock contributions to CA, Inc. Savings Harvest Plan, Non-cash financing activities	23	24
Treasury common shares issued in connection with Employee Stock Purchase Plan, Non-cash financing activities	$ 2	$ 2