Fair Value - Fair Value Measurements on a Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2019	Mar. 31, 2019
Assets:
Money market funds and money market deposit accounts	$ 6	$ 6
Time deposits	217	194
Other debt securities	54	53
Deferred purchase price receivable		574
Total assets	277	827
Liabilities:
Contingent consideration	44	41
Total liabilities	44	41
Level 1
Assets:
Money market funds and money market deposit accounts	6	6
Time deposits	217	194
Other debt securities	0	0
Deferred purchase price receivable		0
Total assets	223	200
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Level 2
Assets:
Money market funds and money market deposit accounts	0	0
Time deposits	0	0
Other debt securities	50	49
Deferred purchase price receivable		0
Total assets	50	49
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Level 3
Assets:
Money market funds and money market deposit accounts	0	0
Time deposits	0	0
Other debt securities	4	4
Deferred purchase price receivable		574
Total assets	4	578
Liabilities:
Contingent consideration	44	41
Total liabilities	44	41
Other Debt Obligations | Level 2
Liabilities:
Cost basis	38	38
Unrealized gains	$ 12	$ 11