Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Income Statements, Captions [Line Items]
Operating revenues, net		$ 167,136	$ 198,547	$ 331,152	$ 402,744
Expenses:
Direct expenses		152,417	168,828	304,971	338,035
Selling, general and administrative expenses		11,778	12,047	23,451	23,284
Total operating expenses		164,195	180,875	328,422	361,319
Loss (gain) on disposal of assets, net		(4,298)	(66)	(3,939)	(73)
Equity in loss of unconsolidated affiliate		76	106	76	174
Operating income		7,163	17,632	6,593	41,324
Interest expense		7,540	7,155	15,073	14,325
Other income, net		(494)	(567)	(1,109)	(1,029)
Total expenses		7,046	6,588	13,964	13,296
Earnings (loss) before income taxes		117	11,044	(7,371)	28,028
Income tax (benefit) expense		(4,160)	4,590	(2,716)	11,211
Net earnings (loss)		4,277	6,454	(4,655)	16,817
Parent Company Only (issuer) [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net		89,365	115,040	181,234	243,697
Expenses:
Direct expenses		89,535	103,483	181,572	209,965
Selling, general and administrative expenses		9,232	9,471	18,275	17,979
Total operating expenses		98,767	112,954	199,847	227,944
Loss (gain) on disposal of assets, net		(4,298)	(66)	(3,939)	(73)
Equity in loss of unconsolidated affiliate		76	106	76	174
Operating income		(5,180)	2,046	(14,750)	15,652
Equity in net income of consolidated subsidiaries		(7,035)	(9,230)	(12,090)	(15,362)
Interest expense		7,534	7,155	15,047	14,325
Other income, net		(819)	(571)	(1,603)	(1,034)
Total expenses		(320)	(2,646)	1,354	(2,071)
Earnings (loss) before income taxes		(4,860)	4,692	(16,104)	17,723
Income tax (benefit) expense		(9,137)	(1,762)	(11,449)	906
Net earnings (loss)		4,277	6,454	(4,655)	16,817
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	[1]	77,771	83,507	149,918	159,047
Expenses:
Direct expenses	[1]	62,882	65,349	123,399	128,079
Selling, general and administrative expenses	[1]	2,871	2,576	5,674	5,305
Total operating expenses	[1]	65,753	67,925	129,073	133,384
Operating income	[1]	12,018	15,582	20,845	25,663
Interest expense	[1]	6		26
Other income, net	[1]			(4)	(4)
Total expenses	[1]	6		22	(4)
Earnings (loss) before income taxes	[1]	12,012	15,582	20,823	25,667
Income tax (benefit) expense	[1]	4,977	6,352	8,733	10,305
Net earnings (loss)	[1]	7,035	9,230	12,090	15,362
Eliminations [Member]
Expenses:
Direct expenses			(4)		(9)
Selling, general and administrative expenses		(325)		(498)
Total operating expenses		(325)	(4)	(498)	(9)
Operating income		325	4	498	9
Equity in net income of consolidated subsidiaries		7,035	9,230	12,090	15,362
Other income, net		325	4	498	9
Total expenses		7,360	9,234	12,588	15,371
Earnings (loss) before income taxes		(7,035)	(9,230)	(12,090)	(15,362)
Net earnings (loss)		$ (7,035)	$ (9,230)	$ (12,090)	$ (15,362)

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