Long-Lived Assets 1 (Details) - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Property and equipment
Total property and equipment	$ 1,102	$ 1,078
Accumulated depreciation	(865)	(841)
Property and equipment, net	237	237	$ 242
Land and Buildings
Property and equipment
Total property and equipment	190	172
Equipment, Software Developed For Internal Use, Furniture and Leasehold Improvements
Property and equipment
Total property and equipment	$ 912	$ 906