Employee Benefit Plans (Net Periodic Benefit Cost, Defined Benefit Pension) (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Service costs	$ 10,564	$ 9,715	$ 10,385
Interest costs	1,301	1,126	800
Expected return on plan assets	(2,167)	(1,792)	(1,724)
Amortization:
Net transition obligation	0	0	4
Net prior service credit recognized	(443)	(51)	(117)
Net actuarial loss recognized	450	242	1,032
Settlement	(97)	0	0
Net periodic benefit cost	$ 9,608	$ 9,240	$ 10,380

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Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan.

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Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

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Amount of transition asset (obligation) recognized in net periodic benefit (cost) credit of defined benefit plan.

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Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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