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Employee Benefit Plans - Summary of Increase (Decrease) in Accumulated Other Comprehensive Loss, Net of Income Tax (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018 | Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total | $ 348 | $ (1,668) | $ (2,493)
Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net actuarial loss (gain) arising during the year | 1,080 | (794) |
Reclassification of stranded tax effects related to the Tax Act |  | 1,771 |
Amortization of actuarial loss | (712) | (788) |
Total | 368 | 189 |
Other Postretirement Benefit Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net actuarial loss (gain) arising during the year | 1 | (57) |
Reclassification of stranded tax effects related to the Tax Act |  | 57 |
Amortization of actuarial loss | (21) | (29) |
Total | $ (20) | $ (29) |

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- Definition Net of tax amount of the income statement impact of the reclassification adjustment for the amortization of actuarial losses recognized as a component of net period benefit cost. + References No definition available. + Details
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- Definition Reclassification from AOCI to retained earnings for stranded tax effects resulting from the Tax Cuts and Job Act of 2017. + References No definition available. + Details
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- Definition Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i-k) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580 + Details
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- Definition Amount, after tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17A -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL34724391-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e689-108580 + Details
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