Acquisitions 3 (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Business Combinations [Abstract]
Accrued acquisition-related costs related to purchase price amounts withheld subject to indemnification protections	$ 10		$ 12
Business Acquisition
Total revenue	1,025	$ 999
Net income (loss)	178	$ 198
Automic and Veracode
Business Acquisition
Total revenue	59
Net income (loss)	$ (19)