Acquisitions - Additional Information (Details)			3 Months Ended								12 Months Ended
	Jan. 05, 2021 USD ($) t	Oct. 01, 2018 USD ($) Employee t	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 164,369,000				$ 150,816,000				$ 164,369,000	$ 150,816,000
Intangible assets, net			81,835,000				83,735,000				81,835,000	83,735,000
Net sales			235,282,000	$ 233,473,000	$ 216,183,000	$ 231,560,000	$ 230,972,000	$ 232,515,000	$ 235,053,000	$ 229,133,000	916,498,000	927,673,000	$ 866,286,000
Operating income											49,156,000	54,635,000	21,942,000
Selling, general and administrative expenses											100,045,000	$ 94,967,000	111,721,000
G-P U.S. Business [Member]
Business Acquisition [Line Items]
Annual sales of acquiree											100,000,000
G P Business [Member]
Business Acquisition [Line Items]
Business acquisition purchase price		$ 188,000,000
Annual production capacity | t		32,000
Business acquisition, date of completion		Oct. 01, 2018
Number of employees at manufacturing facility | Employee		220
Goodwill			74,800,000								74,800,000
Intangible assets, net			43,600,000								43,600,000
Goodwill deductible for tax purposes			$ 0								$ 0
Acquired intangible assets estimated remaining life											13 years
Net sales													23,100,000
Operating income													2,400,000
Selling, general and administrative expenses													$ 5,100,000
G P Business [Member] | Minimum [Member]
Business Acquisition [Line Items]
Acquired property, plant and equipment, estimated remaining lives											5 years
G P Business [Member] | Maximum [Member]
Business Acquisition [Line Items]
Acquired property, plant and equipment, estimated remaining lives											25 years
Subsequent Event [Member] | G-P U.S. Business [Member]
Business Acquisition [Line Items]
Business acquisition purchase price	$ 175,000,000
Annual production capacity | t	37,000