Supplemental Statement of Cash Flows Information 2 (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Supplemental Cash Flow Information [Abstract]
Interest payments	$ 43	$ 32
Income taxes paid, net from continuing operations	202	131
Excess tax benefits from share-based incentive awards included in financing activities from continuing operations	4	3
Share-based incentive awards issued under equity compensation plans, Non-cash financing activities	43	41
Withholding taxes on share-based incentive awards, Non-cash financing activities	33	27
Discretionary stock contributions to CA, Inc. Savings Harvest Plan, Non-cash financing activities	24	24
Treasury common shares issued in connection with Employee Stock Purchase Plan, Non-cash financing activities	$ 2	$ 2