Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Mar. 31, 2019
Deferred tax assets:
Loss carryovers	$ 83	$ 91
Employee benefits	105	54
Accrued liabilities	15	22
Finance lease obligations	2	16
Operating lease obligations	45
Interest expense carryforward	11	11
Other	1	4
Deferred tax assets, gross	262	198
Valuation allowance	(18)	(13)
Deferred tax assets, net of valuation allowance	244	185
Deferred tax liabilities:
Purchased intangible assets	233	312
Fixed assets	53	30
Operating lease assets	42
Other	3	1
Deferred tax liabilities	331	343
Total deferred tax liabilities	$ 87	$ 158