Debt (Additional Information) (Detail)		12 Months Ended
	Feb. 17, 2017 USD ($)	Dec. 31, 2017 USD ($) capital_lease_agreement	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)	Jun. 18, 2015 USD ($)
Debt Instrument [Line Items]
Interest expense on outstanding debt		$ 5,200,000	$ 3,100,000	$ 3,500,000
Unused commitment fee		600,000	400,000	300,000
Deferred debt issuance costs		2,300,000
Amortization expense, debt issue costs		$ 500,000	500,000	500,000
Leverage ratio, cash dividends, maximum		2.75
Capital lease obligation		$ 800,000	5,300,000
Amortization expense related to the capital lease		100,000	300,000	300,000
Capital leases accumulated depreciation		100,000
Interest expense on capital lease		$ 100,000	300,000	$ 400,000
Number of capital lease agreements | capital_lease_agreement		2
Letter of Credit
Debt Instrument [Line Items]
Credit agreement, maximum borrowing capacity			1,200,000.0
Amounts drawn on LOC			0
Maximum
Debt Instrument [Line Items]
Allowed dividend payments		$ 20,000,000
Amended Credit Facility
Debt Instrument [Line Items]
Line of credit facility, additional borrowing capacity						$ 50,000,000
Leverage ratio, maximum		3.25
Maximum leverage ratio option		3.50
Interest coverage ratio, minimum		3.00
Amended Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit agreement, maximum borrowing capacity						295,000,000
Amended Credit Facility | Minimum
Debt Instrument [Line Items]
Interest rate spread over variable rate		0.375%
Unused commitment fee, percentage		0.20%
Amended Credit Facility | Maximum
Debt Instrument [Line Items]
Interest rate spread over variable rate		0.75%
Unused commitment fee, percentage		0.30%
Amended Credit Facility | Bank Term Loan
Debt Instrument [Line Items]
Credit agreement, maximum borrowing capacity						$ 55,000,000
Eurocurrency loans | Minimum
Debt Instrument [Line Items]
Interest rate spread over variable rate		1.375%
Eurocurrency loans | Maximum
Debt Instrument [Line Items]
Interest rate spread over variable rate		1.75%
Third Amended Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Credit agreement, maximum borrowing capacity	$ 450,000,000
Line of credit facility, additional borrowing capacity	$ 175,000,000
Length of credit agreement (years)	5 years
Repayments of lines of credit		$ 110,200,000
Long-term Line of Credit		$ 131,000,000
Federal Funds Rate | Amended Credit Facility
Debt Instrument [Line Items]
Interest rate spread over variable rate		0.50%
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate spread over variable rate		100.00%
London Interbank Offered Rate (LIBOR) | Third Amended Credit Agreement
Debt Instrument [Line Items]
Interest rate spread over variable rate		1.00%
Interest rate swap | Third Amended Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Derivative, amount of hedged item					$ 75,000,000
Germany
Debt Instrument [Line Items]
Capital lease obligation		$ 5,700,000	5,300,000
Amortization expense related to the capital lease		300,000
Capital leases accumulated depreciation		$ 3,300,000	$ 3,400,000