Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidated Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)		$ 4,277	$ 6,454	$ (4,655)	$ 16,817
Unrealized loss on short-term investments		210	(158)	1,017	(19)
Changes in pension plan assets and benefit obligations		1		2
Unrealized realized gain					24
Tax effect		(75)	63	(407)	9
Total comprehensive income (loss)		4,413	6,359	(4,043)	16,831
Parent Company Only (issuer) [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)		4,277	6,454	(4,655)	16,817
Unrealized loss on short-term investments		210	(158)	1,017	(19)
Changes in pension plan assets and benefit obligations		1		2
Unrealized realized gain					24
Tax effect		(75)	63	(407)	9
Total comprehensive income (loss)		4,413	6,359	(4,043)	16,831
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	[1]	7,035	9,230	12,090	15,362
Total comprehensive income (loss)	[1]	7,035	9,230	12,090	15,362
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)		(7,035)	(9,230)	(12,090)	(15,362)
Total comprehensive income (loss)		$ (7,035)	$ (9,230)	$ (12,090)	$ (15,362)

[1] Foreign subsidiaries represent minor subsidiaries and are included in the guarantor subsidiaries' amounts.