Other, Net - Other Net in Consolidated Statements of Income (Detail) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Other Nonoperating Income Expense [Abstract]
Foreign exchange gains (losses)		$ 116	$ (15)		$ 1,169	$ (499)
Investment income		90	49		229	151
Realized and unrealized gains on investments		407	931		504	2,576
Net periodic benefit cost		(129)	(172)		(258)	(343)
Other, net	[1]	$ 484	$ 793	[2]	$ 1,644	$ 1,885	[2]

[1] The 2017 amounts for the noted line items have been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of Accounting Standards Update (ASU) No. 2017-7, Compensation –Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

[2] The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.