Supplementary Information - Property and Equipment (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 588	$ 585
Accumulated depreciation and amortization	(515)	(509)
Total property and equipment, net	73	76
Land
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	13	13
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	498	498
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	17	17
Buildings
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	28	28
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	28	28
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 4	$ 1