Fair Value Measurements - Financial Instruments Measured on a Recurring Basis (Details) - USD ($)				3 Months Ended	9 Months Ended
		Apr. 04, 2017	Jul. 31, 2015	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Recurring
Financial instruments measured at fair value on a recurring basis
Level 1 to level 2 transfers				$ 0	$ 0
Transfers					0
Contingent consideration | Recurring
Financial instruments measured at fair value on a recurring basis
Fair value of liability				47,922,000	47,922,000	$ 44,983,000
Contingent consideration | Recurring | Tax amortization benefit contingency
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[1]			46,276,000	46,276,000	43,382,000
Contingent consideration | Recurring | Contingent consideration related to acquisition
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[2]			1,215,000	1,215,000	691,000
Contingent consideration | Recurring | Interest rate swap
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[3]					456,000
Contingent consideration | Recurring | Stock appreciation rights
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[4]			108,000	108,000	268,000
Contingent consideration | Recurring | Phantom shares
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[5]			323,000	323,000	186,000
Contingent consideration | Recurring | Level 1
Financial instruments measured at fair value on a recurring basis
Fair value of liability				0	0	0
Contingent consideration | Recurring | Level 1 | Tax amortization benefit contingency
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[1]			0	0	0
Contingent consideration | Recurring | Level 1 | Contingent consideration related to acquisition
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[2]			0	0	0
Contingent consideration | Recurring | Level 1 | Interest rate swap
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[3]					0
Contingent consideration | Recurring | Level 1 | Stock appreciation rights
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[4]			0	0	0
Contingent consideration | Recurring | Level 1 | Phantom shares
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[5]			0	0	0
Contingent consideration | Recurring | Level 2
Financial instruments measured at fair value on a recurring basis
Fair value of liability				0	0	456,000
Contingent consideration | Recurring | Level 2 | Tax amortization benefit contingency
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[1]			0	0	0
Contingent consideration | Recurring | Level 2 | Contingent consideration related to acquisition
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[2]			0	0	0
Contingent consideration | Recurring | Level 2 | Interest rate swap
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[3]					456,000
Contingent consideration | Recurring | Level 2 | Stock appreciation rights
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[4]			0	0	0
Contingent consideration | Recurring | Level 2 | Phantom shares
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[5]			0	0	0
Contingent consideration | Recurring | Level 3
Financial instruments measured at fair value on a recurring basis
Fair value of liability				47,922,000	47,922,000	44,527,000
Contingent consideration | Recurring | Level 3 | Tax amortization benefit contingency
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[1]			46,276,000	$ 46,276,000	43,382,000
Tax effect rate					35.30%
Non-current portion new tax rate effect					21.50%
Contingent consideration | Recurring | Level 3 | Contingent consideration related to acquisition
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[2]			1,215,000	$ 1,215,000	691,000
Contingent consideration | Recurring | Level 3 | Interest rate swap
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[3]					0
Contingent consideration | Recurring | Level 3 | Stock appreciation rights
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[4]			108,000	108,000	268,000
Contingent consideration | Recurring | Level 3 | Phantom shares
Financial instruments measured at fair value on a recurring basis
Fair value of liability	[5]			323,000	$ 323,000	$ 186,000
Dow | Tax receivables agreement (TRA)
Financial instruments measured at fair value on a recurring basis
Percentage of tax savings to be paid		50.00%	85.00%
Interest Rate Swap
Financial instruments measured at fair value on a recurring basis
Settlement of derivative				$ 4,000,000

[1] The fair value of the tax amortization benefit contingency is measured using an income approach based on the Company’s best estimate of the undiscounted cash payments to be made, with the current portion tax effected at 35.3% and the non-current portion tax effected at 21.5% due to the TCJA enacted in the U.S and discounted to present value utilizing an appropriate market discount rate. Per the TRA Amendment, payments due to Dow under the Tax Receivable Agreement were reduced from 85% to 50% of the applicable tax savings realized by the Company. The valuation technique used did not change during the nine months ended September 30, 2018.

[2] The fair value of the contingent consideration related to the Tecnidex acquisition.

[3] The interest rate swap relates to an interest rate derivative that is measured at fair value using observable market inputs such as interest rates, our own credit risks as well as an evaluation of the counterparts' credit risks. The swap was settled during the three months ended September 30, 2018 for $4.0 million.

[4] The fair value of the stock appreciation rights was measured using a Black Scholes pricing model during the nine months ended September 30, 2018. The valuation technique used did not change during the nine months ended September 30, 2018.

[5] The fair value of phantom shares is based on the fair value of the Company's common stock. The valuation technique used did not change during the nine months ended September 30, 2018.