Income Taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Comprehensive provision for income taxes (benefit) allocable to:
Income (loss) from continuing operations	$ (15,361)	$ (5,634)	$ (2,777)
Other comprehensive income (loss):
Marketable securities		14,300	10,900
Currency translation	(2,100)	6,100	(1,800)
Interest rate swap		200
Total	(18,100)	16,800	4,000
Defined Benefit Pension Plans
Other comprehensive income (loss):
Defined benefit plans	$ (600)	1,900	(2,100)
OPEB
Other comprehensive income (loss):
Defined benefit plans		$ (100)	$ (200)