Income Taxes - Principal Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax liabilities:
Tax in excess of book depreciation	$ 37,425	$ 34,143
Goodwill	0	58
Intangible assets	80,623	50,688
Other deferred tax liabilities	794	389
Total deferred income tax liabilities	118,842	85,278
Deferred income tax assets:
Interest expense limitation	9,968	0
Goodwill	1,441	2,067
Inventories	2,745	2,248
Pension/Personnel accruals	1,317	1,596
Net operating loss carry forwards	9,321	6,950
Foreign tax credits	5,345	0
Credit carry forwards	4,130	3,427
Accruals and reserves	1,531	2,015
Other deferred tax assets	4,022	3,019
Deferred income tax assets before Valuation Allowance	39,820	21,322
Valuation allowance on deferred tax assets	(14,460)	(7,608)	$ (4,090)	$ (2,376)
Total deferred income tax assets	25,360	13,714
Net deferred income tax liabilities	$ 93,482	$ 71,564