Supplemental Statement of Cash Flows Information 2 (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Supplemental statement of cash flows information
Interest payments	$ 24	$ 24
Income taxes paid, net	30	47
Treasury common shares issued in connection with share-based incentive awards under equity compensation plans, Non-cash financing activities	46	45
Withholding taxes on share-based incentive awards, Non-cash financing activities	40	34
Treasury common shares issued in connection with discretionary stock contributions to CA, Inc. Savings Harvest Plan, Non-cash financing activities	24	23
Treasury common shares issued in connection with Employee Stock Purchase Plan, Non-cash financing activities	$ 2	$ 2