Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidated Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Net (loss) earnings	$ (3,277)	$ (4,967)	$ (21,798)	$ (9,622)
Unrealized gain (loss) on short-term investments	41	(494)	370	523
Changes in pension plan asset and benefit obligation	(24)	1	(2)	3
Tax effect of the above-listed adjustments	(8)	178	(134)	(229)
Total comprehensive (loss) income	(3,268)	(5,282)	(21,564)	(9,325)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) earnings	(14,850)	(8,372)	(32,093)	(20,462)
Total comprehensive (loss) income	(14,850)	(8,372)	(32,093)	(20,462)
Parent Company Only (issuer) [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) earnings	(3,277)	(4,967)	(21,798)	(9,622)
Unrealized gain (loss) on short-term investments	41	(494)	370	523
Changes in pension plan asset and benefit obligation	(24)	1	(2)	3
Tax effect of the above-listed adjustments	(8)	178	(134)	(229)
Total comprehensive (loss) income	(3,268)	(5,282)	(21,564)	(9,325)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) earnings	16,305	8,372	33,686	20,462
Total comprehensive (loss) income	16,305	$ 8,372	33,686	$ 20,462
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net (loss) earnings	(1,455)		(1,593)
Total comprehensive (loss) income	$ (1,455)		$ (1,593)