Income Taxes - Tax Cuts and Jobs Act (Details) - USD ($)			3 Months Ended	4 Months Ended	8 Months Ended	12 Months Ended
Jan. 01, 2018	Dec. 31, 2017	Jan. 27, 2018	Apr. 30, 2018	Dec. 31, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Income Taxes
U.S. federal statutory income tax rate (as a percent)	21.00%	35.00%		21.00%	35.00%	21.00%	30.40%	34.00%
Deferred tax expense			$ 3,100,000			$ 3,300,000	$ 3,300,000

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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