Fair Value - Fair Value Measurements on a Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2021	Mar. 31, 2021
ASSETS
Other securities	$ 58	$ 57
Total assets	154	147
Liabilities:
Contingent consideration	20	27
Total liabilities	20	27
Level 1
ASSETS
Other securities	0	0
Total assets	96	90
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Level 2
ASSETS
Other securities	55	55
Total assets	55	55
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Cost basis	56	57
Unrealized losses	(1)	(2)
Level 3
ASSETS
Other securities	3	2
Total assets	3	2
Liabilities:
Contingent consideration	20	27
Total liabilities	20	27
Money market funds and money market deposit accounts
ASSETS
Cash and cash equivalents	13	12
Money market funds and money market deposit accounts | Level 1
ASSETS
Cash and cash equivalents	13	12
Money market funds and money market deposit accounts | Level 2
ASSETS
Cash and cash equivalents	0	0
Money market funds and money market deposit accounts | Level 3
ASSETS
Cash and cash equivalents	0	0
Time deposits
ASSETS
Cash and cash equivalents	83	78
Time deposits | Level 1
ASSETS
Cash and cash equivalents	83	78
Time deposits | Level 2
ASSETS
Cash and cash equivalents	0	0
Time deposits | Level 3
ASSETS
Cash and cash equivalents	$ 0	$ 0