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Schedule of Effective Tax Rate Applicable to Pre-Tax Earnings (Detail) | 4 Months Ended | 5 Months Ended | 12 Months Ended
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Jul. 31, 2017 | Dec. 31, 2017 | Mar. 31, 2017
Schedule Of Effective Tax Rate Reconciliation [Line Items] |  |  |
Effective tax rate applicable to pre-tax earnings |  | (5.50%) |
Predecessor |  |  |
Schedule Of Effective Tax Rate Reconciliation [Line Items] |  |  |
Effective tax rate applicable to pre-tax earnings | 0.10% |  | (0.99%)

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 + Details
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