Retirement Benefit Plans - Reconciliation of Defined Benefit Pension Plan (Details) - Defined Benefit Pension Plan - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Change in benefit obligation:
Benefit obligation at beginning of year	$ 3,883	$ 4,027
Interest cost	88	107
Plan amendment	46	0
Actuarial gain	(243)	(233)
Benefits paid	(882)	(455)
Foreign currency impact	(262)	437
Benefit obligation at end of year	2,630	3,883
Change in plan assets:
Fair value of assets at beginning of year	4,453	3,929
Actual return on plan assets	105	451
Employer contributions	131	66
Benefits paid	(882)	(455)
Foreign currency impact	(304)	462
Fair value of assets at end of year	3,503	4,453
Funded status as of March 31, 2019 and 2018	$ 873	$ 570

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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