Credit Facilities and Debt - Additional Information - PM Group Short-Term Working Capital Borrowing (Detail) - 9 months ended Sep. 30, 2017 - Short-term Working Capital Borrowings [Member] - PM Group [Member] € in Thousands, $ in Thousands	USD ($) Bank	EUR (€) Bank
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 30,131	€ 25,507
Short-term Debt	$ 25,205	€ 21,337
Italy [Member]
Line of Credit Facility [Line Items]
Number of banks which PM Group established demand credit and overdraft facilities	7	7
Short-term Debt	$ 24,507	€ 20,746
Italy [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Variable interest rate	1.42%	1.42%
Italy [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Variable interest rate	1.67%	1.67%
South America [Member]
Line of Credit Facility [Line Items]
Number of banks which PM Group established demand credit and overdraft facilities	6	6
Short-term Debt	$ 698	€ 591
South America [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Working capital borrowing interest rate	9.00%	9.00%
South America [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Working capital borrowing interest rate	24.00%	24.00%
3-month or 6-month Euribor [Member] | Advances on orders, invoices, and letter of credit [Member] | Italy [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
3-month Euribor [Member] | Bank Overdrafts [Member] | Italy [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.50%