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Employee Benefit Plans - Additional Information (Detail) shares in Thousands | 12 Months Ended
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Mar. 31, 2017 USD ($) $ / Employee | Mar. 31, 2016 USD ($) shares | Mar. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employee's years of service and average earnings | Five highest consecutive calendar years of compensation in the ten-year period preceding retirement |  |
Accumulated benefit obligation | $ 30,678,000 | $ 32,270,000 |
Contribution equal to employee salary deferral | 100.00% |  |
Employer contribution description | Matching contributions equal to 100% of the first 3% of an employee’s salary deferral and 50% of the next 2% percent of an employee’s salary deferral |  |
Contribution next to employee salary deferral | 3.00% |  |
Contribution for additional employee salary deferral | 50.00% |  |
Contribution additional next to employee salary deferral | 2.00% |  |
Share of the medical premium cost for family coverage | $ 4,000 |  |
Share of the medical premium cost for single coverage | 2,000 |  |
Share of the medical premium both family and single coverage for regular retirees | $ 1,000 |  |
Medical care cost trend rate | 5.00% |  |
Medical care trend year | 2023 |  |
Medical care cost trend rate decrements | 0.50% |  |
Current portion of accrued postretirement benefit obligation | $ 83,000 | $ 88,000 |
Employee stock ownership plan, shares | shares |  | 202 |
Company contributions to the ESOP | $ 0 | $ 0 | $ 0
Stop loss coverage per employee for claims | $ / Employee | 100 |  |
Maximum aggregate stop loss coverage | $ / Employee | 1,000 |  |
Total plan amount | $ 2,479,000 |  |
Self-Insured medical plan liability | 174,000 | 176,000 |
Defined Contribution Plan 401K [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Contributions to defined contribution plan | 873,000 | 866,000 | 940,000
Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Liability released through annuity purchase | (1,118,000) | (1,710,000) |
Annuities purchased | (1,246,000) | (1,798,000) |
Estimated net actuarial loss for pension plan | 1,013,000 |  |
Pension expense | $ 528,000 | $ (49,000) | $ (469,000)
Weighted average discount rates used to develop net postretirement benefit cost | 3.93% | 3.74% | 4.46%
Defined Contribution Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Contributions to defined contribution plan | $ 286,000 | $ 315,000 | $ 294,000
Supplemental Executive Retirement Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension expense | 128,000 | 76,000 | 70,000
Pension expense related liability | 493,000 | 391,000 |
Current portion of the related liability included in accrued compensation | 26,000 | 26,000 |
Other Postretirement Benefit Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated net actuarial loss for pension plan | 37,000 |  |
Pension expense | $ 62,000 | $ 69,000 | $ (40,000)
Weighted average discount rates used to develop net postretirement benefit cost | 3.16% | 3.11% | 3.59%

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- Definition Aggregate annual stop loss coverage for the entire medical plan. + References No definition available. + Details
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- Definition Company's share of the medical premium cost for early retirees for family coverage under the other postretirement plan. + References No definition available. + Details
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- Definition Company's share of the medical premium cost for early retirees for single coverage under the other postretirement plan. + References No definition available. + Details
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- Definition Company's share of the medical premium cost for regular retirees for coverage under the other postretirement plan. + References No definition available. + Details
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- Definition The employer matching contribution percentage on the 2% employee salary deferral after the first 3% employee salary deferral. + References No definition available. + Details
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- Definition Annual decrement percentage in the defined benefit plan health care cost trend rate used to reach the ultimate health care cost trend rate. + References No definition available. + Details
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- Definition Percentage of employee's first 3% salary deferral for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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- Definition The employee deferral percentage that receives a 50% employer matching contribution. + References No definition available. + Details
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- Definition For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503844 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition 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. + References No definition available. + Details
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- Definition The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition The amount of decrease that relates to an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 15 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=7577095&loc=d3e8001-114927 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(10) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition Amount of plan assets that relate to an irrevocable action that relieves the employer, or plan, of primary responsibility for a benefit obligation and eliminates risks related to the obligation and the assets used to effect settlement. Includes, but is not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified pension benefits and purchasing annuity contracts to cover vested benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 35 -Paragraph 123 -Subparagraph B -URI http://asc.fasb.org/extlink&oid=64937487&loc=d3e36068-114959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 63 -Subparagraph B -URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12551-114930 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 15 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=7577095&loc=d3e8001-114927 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 35 -Paragraph 126 -Subparagraph B -URI http://asc.fasb.org/extlink&oid=64937487&loc=d3e36091-114959 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(8) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 66 -Subparagraph B -URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12688-114930 + Details
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- Definition The ultimate trend rate for health care costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Definition Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65895303&loc=d3e17540-113929 + Details
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