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, 2019	Dec. 31, 2018
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					$ 91,654,000	$ 90,247,000
Fair value of plan assets at end of the period					59,625,000	56,790,000
Pension Plans, Defined Benefit
Schedule of Pension and Other Postretirement Benefits Changes in Benefit Obligation and Fair Value of Plan Assets [Line Items]
Actuarial (gain) loss		$ 748,000
Employer contributions				$ 0	1,100,000	0
Fair value of plan assets at end of the period					59,095,000	56,209,000
Current liabilities		(1,791,000)	$ (10,731,000)	(10,731,000)	(1,422,000)	(1,380,000)
Noncurrent liabilities		(41,642,000)	(35,252,000)	(35,252,000)	(30,607,000)	(32,161,000)
Net amount recognized		(43,433,000)	(45,983,000)	(45,983,000)	(32,029,000)	(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		(109,000)	(217,000)		983,000	(275,000)
Settlement					(4,638,000)	(8,885,000)
Fair value of plan assets at beginning of the period		57,146,000	58,148,000	57,146,000	56,790,000	57,536,000
Actual return		2,138,000	1,182,000		7,498,000	(2,128,000)
Expected return		16,000	32,000			112,000
Administrative expenses		(7,000)	(15,000)		(68,000)	(36,000)
Plan curtailment			(100,000)
Employer contributions		435,000	625,000		5,027,000	10,546,000
Benefits paid		(1,610,000)	(2,059,000)		(5,967,000)	(5,467,000)
Foreign currency exchange rate changes		139,000	(60,000)			(76,000)
Fair value of plan assets at end of the period		58,148,000	57,536,000	57,536,000	59,625,000	56,790,000
Payroll tax unrecognized in benefit obligation at end of the period		91,000	76,000	76,000		84,000
Unfunded status at end of the period		(43,433,000)	(45,983,000)		(32,029,000)	(33,541,000)
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		97,941,000	101,490,000	97,941,000	90,247,000	103,443,000
Increase in benefit obligation and plan assets due to business combination						5,474,000
Service cost		393,000	546,000		427,000	294,000
Interest cost		1,313,000	1,599,000		3,751,000	3,605,000
Plan curtailment			(432,000)
Benefits paid		(1,610,000)	(2,059,000)		(5,967,000)	(5,467,000)
Actuarial (gain) loss	[1]	3,322,000	2,322,000		8,198,000	(8,105,000)
Settlement					(4,978,000)	(8,885,000)
Foreign currency exchange rate changes		131,000	(23,000)		(24,000)	(112,000)
Benefit obligation at end of the period		101,490,000	103,443,000	103,443,000	$ 91,654,000	90,247,000
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		(335,000)				554,000
Current liabilities		(418,000)	(282,000)	(282,000)
Noncurrent liabilities		(4,399,000)	(2,642,000)	(2,642,000)
Net amount recognized		(4,817,000)	(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		288,000	461,000			377,000
Participant contributions		58,000	65,000			218,000
Benefits paid		(346,000)	(526,000)			(595,000)
Unfunded status at end of the period		(4,817,000)	(2,924,000)
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		4,811,000	4,817,000	4,811,000		2,924,000
Service cost		23,000	29,000			61,000
Interest cost		64,000	75,000			117,000
Participant contributions		58,000	65,000			218,000
Plan amendment			(1,861,000)			(2,954,000)
Benefits paid		(346,000)	(526,000)			(595,000)
Actuarial (gain) loss		207,000	325,000			$ 229,000
Benefit obligation at end of the period		$ 4,817,000	$ 2,924,000	$ 2,924,000

[1] The actuarial loss for the year ended December 31, 2019 and the actuarial gain in the year ended December 31, 2018  was primarily attributable to changes in the discount rate.