Income Taxes - Components Of Deferred Tax Balances (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Assets
Receivable allowances	$ 70	$ 58
Compensation and benefit related accruals	377	345
Net operating loss and credit carryforwards	885	811
Long-term contractual obligations	0	59
Other	216	279
Subtotal	1,548	1,552
Less: valuation allowance	(870)	(751)
Total assets	678	801
Liabilities
Inventory valuation and other assets	(2,016)	(1,869)
Fixed assets and systems development costs	(170)	(158)
Intangibles	(513)	(644)
Change Healthcare Equity Investment	(885)	(814)
Other	(34)	(71)
Total liabilities	(3,618)	(3,556)
Net deferred tax liability	(2,940)	(2,755)
Long-term deferred tax asset	58	49
Long-term deferred tax liability	$ (2,998)	$ (2,804)