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Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies - Weighted Average Shares of Unvested Restricted Stock (Detail) - shares shares in Thousands	1 Months Ended	2 Months Ended	3 Months Ended	7 Months Ended	9 Months Ended
	Aug. 13, 2018	Sep. 30, 2018	Sep. 30, 2017	Aug. 13, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested restricted stock		396
Predecessor
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested restricted stock	813		666	839	612