Change in Plan Assets and Obligations (Detail) - USD ($)		4 Months Ended	5 Months Ended	9 Months Ended	12 Months Ended
		Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Mar. 31, 2017
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at end of the period					$ 90,247,000
Fair value of plan assets at end of the period					56,790,000
Predecessor
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at end of the period			$ 103,443,000	$ 103,443,000
Fair value of plan assets at end of the period			57,536,000	57,536,000
Pension Plans, Defined Benefit
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Employer contributions				0	0	$ 3,000,000
Fair value of plan assets at end of the period			56,928,000	56,928,000	56,209,000
Current liabilities			(10,731,000)	(10,731,000)	(1,380,000)
Noncurrent liabilities			(35,252,000)	(35,252,000)	(32,161,000)
Net amount recognized			(45,983,000)	(45,983,000)	(33,541,000)
Pension Plans, Defined Benefit | Change In Plan Assets
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Increase in benefit obligation and plan assets due to business combination					5,463,000
Actuarial (gain) loss			(217,000)		(275,000)
Settlement					(8,885,000)
Fair value of plan assets at beginning of the period			58,148,000		57,536,000
Actual return			1,182,000		(2,128,000)
Expected return			32,000		112,000
Administrative expenses			(15,000)		(36,000)
Plan curtailment			(100,000)
Employer contributions			625,000		10,546,000
Benefits paid			(2,059,000)		(5,467,000)
Foreign currency exchange rate changes			(60,000)		(76,000)
Fair value of plan assets at end of the period			57,536,000	57,536,000	56,790,000
Payroll tax unrecognized in benefit obligation at end of the period			76,000	76,000	84,000
Unfunded status at end of the period			(45,983,000)		(33,541,000)
Pension Plans, Defined Benefit | Predecessor
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Actuarial (gain) loss		$ 748,000				1,785,000
Current liabilities		(1,791,000)				(1,791,000)
Noncurrent liabilities		(41,642,000)				(39,087,000)
Net amount recognized		(43,433,000)				(40,878,000)
Pension Plans, Defined Benefit | Predecessor | Change In Plan Assets
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Actuarial (gain) loss		(109,000)				(148,000)
Fair value of plan assets at beginning of the period		57,146,000		57,146,000		57,174,000
Actual return		2,138,000				577,000
Expected return		16,000				51,000
Administrative expenses		(7,000)				(27,000)
Employer contributions		435,000				4,465,000
Benefits paid		(1,610,000)				(4,895,000)
Foreign currency exchange rate changes		139,000				(51,000)
Fair value of plan assets at end of the period		58,148,000				57,146,000
Payroll tax unrecognized in benefit obligation at end of the period		91,000				83,000
Unfunded status at end of the period		(43,433,000)				(40,878,000)
Pension Plans, Defined Benefit | Change in Benefit Obligations
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at beginning of the period			101,490,000		103,443,000
Increase in benefit obligation and plan assets due to business combination					5,474,000
Service cost			546,000		294,000
Interest cost			1,599,000		3,605,000
Plan curtailment			(432,000)
Benefits paid			(2,059,000)		(5,467,000)
Actuarial (gain) loss	[1]		2,322,000		(8,105,000)
Settlement					(8,885,000)
Foreign currency exchange rate changes			(23,000)		(112,000)
Benefit obligation at end of the period			103,443,000	103,443,000	90,247,000
Pension Plans, Defined Benefit | Change in Benefit Obligations | Predecessor
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at beginning of the period		97,941,000		97,941,000		95,830,000
Service cost		393,000				1,182,000
Interest cost		1,313,000				3,814,000
Benefits paid		(1,610,000)				(4,895,000)
Actuarial (gain) loss	[1]	3,322,000				2,082,000
Foreign currency exchange rate changes		131,000				(72,000)
Benefit obligation at end of the period		101,490,000				97,941,000
Other Pension Plan
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Actuarial (gain) loss					554,000
Current liabilities			(282,000)	(282,000)
Noncurrent liabilities			(2,642,000)	(2,642,000)
Net amount recognized			(2,924,000)	(2,924,000)
Other Pension Plan | Change In Plan Assets
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Employer contributions			461,000		377,000
Participant contributions			65,000		218,000
Benefits paid			(526,000)		(595,000)
Unfunded status at end of the period			(2,924,000)
Other Pension Plan | Predecessor
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Actuarial (gain) loss		(335,000)				(1,138,000)
Current liabilities		(418,000)				(418,000)
Noncurrent liabilities		(4,399,000)				(4,393,000)
Net amount recognized		(4,817,000)				(4,811,000)
Other Pension Plan | Predecessor | Change In Plan Assets
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Employer contributions		288,000				759,000
Participant contributions		58,000				411,000
Benefits paid		(346,000)				(1,170,000)
Unfunded status at end of the period		(4,817,000)				(4,811,000)
Other Pension Plan | Change in Benefit Obligations
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at beginning of the period			4,817,000		2,924,000
Service cost			29,000		61,000
Interest cost			75,000		117,000
Participant contributions			65,000		218,000
Plan amendment			(1,861,000)		(2,954,000)
Benefits paid			(526,000)		(595,000)
Actuarial (gain) loss			325,000		$ 229,000
Benefit obligation at end of the period			$ 2,924,000	2,924,000
Other Pension Plan | Change in Benefit Obligations | Predecessor
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Benefit obligation at beginning of the period		4,811,000		$ 4,811,000		5,573,000
Service cost		23,000				81,000
Interest cost		64,000				201,000
Participant contributions		58,000				411,000
Benefits paid		(346,000)				(1,170,000)
Actuarial (gain) loss		207,000				(285,000)
Benefit obligation at end of the period		$ 4,817,000				$ 4,811,000

[1] The actuarial gain in the twelve months ended December 31, 2018 was primarily attributable to an increase in the discount rate.