Other Investments (Summary of Other Investments) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 274,391
Current Assets [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	15,154
Other Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	259,237
Significant Other Observable Inputs (Level 2)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Amortized Costs	42,326
Debt Securities, Unrealized Gains	1,571
Debt Securities, Unrealized Losses	0	$ 0
Debt Securities, Fair Value	43,897
Forward Purchase Contracts, Amortized Costs	232,929
Forward Purchase Contracts, Unrealized Gains	0	$ 0
Forward Purchase Contracts, Unrealized Losses	(2,435)
Forward Purchase Contracts, Fair Value	$ 230,494

Equity Securities Accumulated Gross Unrealized Gain Before Tax

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Equity Securities, Accumulated Gross Unrealized Loss, before Tax

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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