Fair Value - Fair Value Measurements on a Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2017	Mar. 31, 2017
Assets:
Money market funds and money market deposit accounts	$ 232	$ 406
Time deposits	292
Foreign bonds	51
Other debt securities	6
Deferred purchase price receivable	272	252
Total assets	853	658
Liabilities:
Contingent consideration	7	7
Total liabilities	7	7
Level 1
Assets:
Money market funds and money market deposit accounts	232	406
Time deposits	292
Foreign bonds	0
Other debt securities	0
Deferred purchase price receivable	0	0
Total assets	524	406
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
Foreign bonds	51
Other debt securities	0
Deferred purchase price receivable	0	0
Total assets	51	0
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
Foreign bonds	0
Other debt securities	6
Deferred purchase price receivable	272	252
Total assets	278	252
Liabilities:
Contingent consideration	7	7
Total liabilities	$ 7	$ 7