Senior Debt - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Line Of Credit Facility [Line Items]
Prepayment of outstanding debt	$ 13,000,000	$ 23,300,000
Long-term debt, principal payment remainder of 2016	2,100,000	2,100,000
Long-term debt, principal payment 2017	9,300,000	9,300,000
Long-term debt, principal payment 2018	12,100,000	12,100,000
Long-term debt, principal payment 2019	14,300,000	14,300,000
Long-term debt, principal payment 2020	$ 97,400,000	$ 97,400,000
Weighted average interest rate on outstanding borrowings	3.19%	3.19%	3.42%
Interest rate swap, fair value	$ 1,200,000	$ 1,200,000	$ 400,000
Changes in fair value income (loss)		500,000
ING Bank N.V. ("Aarding") [Member]
Line Of Credit Facility [Line Items]
Total borrowing capacity	14,600,000	14,600,000	14,600,000
ING Bank N.V. ("Aarding") [Member] | Bank Overdrafts [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities	300,000	300,000	5,300,000
Letters of Credit [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities	16,900,000	16,900,000	15,400,000
Bank Guarantee Facility [Member] | ING Bank N.V. ("Aarding") [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities	2,400,000	2,400,000	6,600,000
China Facility [Member]
Line Of Credit Facility [Line Items]
Aggregate principal amount outstanding under the credit facilities	$ 1,400,000	$ 1,400,000
Interest rate	4.79%	4.79%
Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Unused credit availability under credit facility	$ 63,100,000	$ 63,100,000	$ 56,600,000