Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	$ 284,115
Balance at end of period	300,052
Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period		$ 46,069
Change in accounting principle- ASU 2016-01		(46,069)
Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(172,434)	(164,467)
Other comprehensive income (loss)	733	3,501
Balance at end of period	(172,459)	(161,876)
Accumulated Defined Benefit Plans Adjustment | Defined Benefit Pension Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(75,286)	(72,951)
Other comprehensive income (loss)	828	983
Balance at end of period	(74,458)	(71,968)
Accumulated Defined Benefit Plans Adjustment | OPEB
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(550)	(388)
Other comprehensive income (loss)	(70)	(73)
Balance at end of period	(620)	(461)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(248,270)	(191,737)
Change in accounting principle- ASU 2016-01		(46,069)
Balance at beginning of period, as adjusted	(248,270)	(237,806)
Other comprehensive income (loss)	(25)	2,591
Balance at end of period	$ (247,537)	$ (234,305)