Income Taxes, Reconciliation Between the U.S. Federal Statutory Rate and the Effective Tax Rate (Details)	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Reconciliation of federal statutory income tax rate to company's effective income tax rate [Abstract]
Statutory federal tax	21.00%	31.50%	35.00%
State taxes, net of federal benefit	3.60%	2.90%	(3.30%)
Taxes on non-U.S. earnings and losses	3.90%	(3.80%)	(3.50%)
Valuation allowances	4.00%	(5.60%)	1.20%
Tax credits	(26.10%)	(17.30%)	(9.00%)
Compensation	(0.10%)	(0.80%)	2.90%
Tax rate or law changes	(12.00%)	60.10%	(2.50%)
Uncertain tax positions, net of settlements	0.40%	(0.80%)	5.60%
Notional interest deductions	(2.50%)	(3.20%)	(8.80%)
Dividend repatriation	1.60%	0.20%	7.10%
Other	(0.10%)	(0.80%)	3.70%
Effective tax rate	(6.30%)	62.40%	28.40%

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax contingencies. Includes, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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