Retirement Plans (Schedule of Changes in Projected Benefit Obligations) (detail) (USD $)	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations at beginning of year	$ 170,478,000	$ 163,531,000
Service cost	8,515,000us-gaap_DefinedBenefitPlanServiceCost	7,752,000us-gaap_DefinedBenefitPlanServiceCost	6,988,000us-gaap_DefinedBenefitPlanServiceCost
Interest cost	8,236,000us-gaap_DefinedBenefitPlanInterestCost	7,592,000us-gaap_DefinedBenefitPlanInterestCost	7,265,000us-gaap_DefinedBenefitPlanInterestCost
Plan Amendments	952,000
Actuarial (gain) loss	30,556,000	(3,109,000)
Benefits payments and expenses	(5,829,000)us-gaap_DefinedBenefitPlanBenefitsPaid	(5,288,000)us-gaap_DefinedBenefitPlanBenefitsPaid
Benefit obligation at end of year	212,908,000	170,478,000	163,531,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	154,650,000	135,016,000
Actual gain on plan assets	8,777,000	22,922,000
Employer contributions	350,000	2,000,000
Benefits payments and expenses	(5,829,000)us-gaap_DefinedBenefitPlanBenefitsPaid	(5,288,000)us-gaap_DefinedBenefitPlanBenefitsPaid
Fair value of plan assets at end of year	157,948,000	154,650,000	135,016,000
Unfunded Status	$ 54,960,000	$ 15,828,000

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)

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-Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost)

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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

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The increase in the fair value of plan assets from contributions made by the employer.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The amount of increase or decrease due to a change in the terms of an existing plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

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