Schedule of Other Changes in Plan Assets and Benefit Obligation Recognized (Detail) - USD ($) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Pension Plans, Defined Benefit
Schedule Of Accumulated Benefit Obligations In Excess Of Fair Value Of Plan Assets And Amounts Recognized In Balance Sheet And In Other Comprehensive Income Loss [Line Items]
Net (gain) loss	$ 1,877	$ 1,939	$ 2,612	$ (3,441)
Fresh-start accounting fair value adjustment	(22,333)
Recognized actuarial loss	(748)
Net curtailment gain			(182)	(335)
Total recognized in other comprehensive (income) loss, before tax and net of tax	(21,204)	1,939	$ 2,430	(3,776)
Fresh-start accounting fair value adjustment	22,333
Recognized actuarial (gain)	(748)
Other Pension Plan
Schedule Of Accumulated Benefit Obligations In Excess Of Fair Value Of Plan Assets And Amounts Recognized In Balance Sheet And In Other Comprehensive Income Loss [Line Items]
Net (gain) loss	207	325		229
Prior service (cost) credit		(1,861)
Amortization of prior service cost	927			1,861
Fresh-start accounting fair value adjustment	(19,055)
Recognized actuarial loss	335			(554)
Total recognized in other comprehensive (income) loss, before tax and net of tax	20,524	$ (1,536)		1,536
Fresh-start accounting fair value adjustment	19,055
Recognized actuarial (gain)	$ 335			$ (554)