Borrowing Arrangements - Additional Information (Detail) € in Thousands, ¥ in Thousands, £ in Thousands		12 Months Ended
	May 20, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 GBP (£)	Dec. 31, 2017 CNY (¥)	Mar. 02, 2017 USD ($)
Line Of Credit Facility [Line Items]
Agreement borrowing capacity		$ 800,000			€ 400	£ 250
Credit amount outstanding		0	$ 0
Future principal payments, next twelve months		19,335,000
Future principal payments, in year two		25,844,000
Future principal payments, in year three		344,000
Future principal payments, in year four		20,585,000
Future principal payments, in year five		45,000
Deferred financing fees		1,250,000
Issuance of debt to acquire net assets of Åkers (Note 2)		0	22,619,000	$ 0
Accrued interest		2,697,000	2,274,000
Industrial Revenue Bonds ("IRB") [Member]
Line Of Credit Facility [Line Items]
Long term debt		13,311,000	13,311,000
Promissory Notes (and Interest) [Member]
Line Of Credit Facility [Line Items]
Long term debt		$ 25,395,000	23,844,000
Debt, interest rate		6.50%			6.50%	6.50%	6.50%
Accrued interest		$ 2,776,000
Debt, maturity date		Mar. 03, 2019
Promissory Notes (and Interest) [Member] | Akers AB [Member]
Line Of Credit Facility [Line Items]
Issuance of debt to acquire net assets of Åkers (Note 2)		$ 22,619,000
Minority Shareholder Loan [Member]
Line Of Credit Facility [Line Items]
Long term debt		$ 5,325,000	4,990,000				¥ 34,655
Debt, interest rate		5.00%			5.00%	5.00%	5.00%
Accrued interest		$ 2,682,000					¥ 17,457
Minimum [Member] | Capital Leases [Member]
Line Of Credit Facility [Line Items]
Effective interest rate		1.30%			1.30%	1.30%	1.30%
Maximum [Member] | Capital Leases [Member]
Line Of Credit Facility [Line Items]
Effective interest rate		5.20%			5.20%	5.20%	5.20%
Tax Exempt Industrial Revenue Bond One [Member] | Industrial Revenue Bonds ("IRB") [Member]
Line Of Credit Facility [Line Items]
Tax-exempt IRB maturing in 2020/2027/2029		$ 4,120,000
Interest at a floating rate on tax-exempt IRB maturing in 2020/2027/2029		0.91%			0.91%	0.91%	0.91%
Taxable Industrial Revenue Bond [Member] | Industrial Revenue Bonds ("IRB") [Member]
Line Of Credit Facility [Line Items]
Tax-exempt IRB maturing in 2020/2027/2029		$ 7,116,000
Interest at a floating rate on tax-exempt IRB maturing in 2020/2027/2029		1.17%			1.17%	1.17%	1.17%
Tax Exempt Industrial Revenue Bond Two [Member] | Industrial Revenue Bonds ("IRB") [Member]
Line Of Credit Facility [Line Items]
Tax-exempt IRB maturing in 2020/2027/2029		$ 2,075,000
Interest at a floating rate on tax-exempt IRB maturing in 2020/2027/2029		0.79%			0.79%	0.79%	0.79%
Revolving Credit and Security Agreement [Member]
Line Of Credit Facility [Line Items]
Initial term of credit facility	5 years
Agreement borrowing capacity	$ 100,000,000
Additional borrowing capacity	$ 50,000,000
Long term debt		$ 20,349,000	$ 0
Interest on outstanding balance		2.75%
Line of credit, remaining borrowing capacity		$ 56,000,000
Revolving Credit and Security Agreement [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Commitment fee payable percentage	0.25%
Revolving Credit and Security Agreement [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Commitment fee payable percentage	0.375%
Fixed charge coverage ratio		1.00			1.00	1.00	1.00
Revolving Credit and Security Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line Of Credit Facility [Line Items]
Debt instrument description of interest rate		LIBOR plus an applicable margin ranging between 1.25% to 1.75%
Revolving Credit and Security Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Debt instrument basis spread	1.25%
Revolving Credit and Security Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Debt instrument basis spread	1.75%
Revolving Credit and Security Agreement [Member] | Base Rate [Member]
Line Of Credit Facility [Line Items]
Debt instrument description of interest rate		the base rate plus an applicable margin ranging between 0.25% to 0.75%
Revolving Credit and Security Agreement [Member] | Base Rate [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Debt instrument basis spread	0.25%
Revolving Credit and Security Agreement [Member] | Base Rate [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Debt instrument basis spread	0.75%
Revolving Credit and Security Agreement [Member] | Letter of Credit [Member]
Line Of Credit Facility [Line Items]
Agreement borrowing capacity								$ 40,000,000
Revolving Credit and Security Agreement [Member] | European Credit Facility [Member]
Line Of Credit Facility [Line Items]
Agreement borrowing capacity								15,000,000
Long term debt | £						£ 1,000
Revolving Credit and Security Agreement [Member] | Canadian Credit Facility [Member]
Line Of Credit Facility [Line Items]
Agreement borrowing capacity								$ 15,000,000