Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	$ 150,167	$ 158,093	$ 431,209	$ 489,245
Expenses:
Direct expenses	136,786	144,938	400,250	449,909
Selling, general and administrative expenses	11,401	13,381	38,691	36,832
Total operating expenses	148,187	158,319	438,941	486,741
Gain (loss) on disposal of assets	(4)	85	3	(3,854)
Equity in loss of unconsolidated affiliate, net	(438)	198	1,556	274
Operating (loss) income	2,422	(509)	(9,291)	6,084
Equity in net income of consolidated subsidiaries				0
Interest expense	8,027	7,719	24,305	22,792
Other income, net	(706)	(462)	(2,474)	(1,571)
Total expenses	7,321	7,257	21,831	21,221
(Loss) earnings before income taxes	(4,899)	(7,766)	(31,122)	(15,137)
Income tax benefit	(1,622)	(2,799)	(9,324)	(5,515)
Net (loss) earnings	(3,277)	(4,967)	(21,798)	(9,622)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	(7,953)		(10,773)
Expenses:
Direct expenses	(7,953)		(10,773)	0
Selling, general and administrative expenses	(4)	(350)	(14)	(848)
Total operating expenses	(7,957)	(350)	(10,787)	(848)
Equity in loss of unconsolidated affiliate, net		0		0
Operating (loss) income	4	350	14	848
Equity in net income of consolidated subsidiaries	14,850	8,372	32,093	20,462
Interest expense				0
Other income, net	4	350	14	848
Total expenses	14,854	8,722	32,107	21,310
(Loss) earnings before income taxes	(14,850)	(8,372)	(32,093)	(20,462)
Income tax benefit				0
Net (loss) earnings	(14,850)	(8,372)	(32,093)	(20,462)
Parent Company Only (issuer) [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	79,644	79,532	228,973	260,766
Expenses:
Direct expenses	83,727	83,188	238,669	264,761
Selling, general and administrative expenses	8,240	10,639	29,265	28,914
Total operating expenses	91,967	93,827	267,934	293,675
Gain (loss) on disposal of assets	(4)	85	4	(3,854)
Equity in loss of unconsolidated affiliate, net	112	198	1,040	274
Operating (loss) income	(12,431)	(14,578)	(40,005)	(29,329)
Equity in net income of consolidated subsidiaries	(14,850)	(8,372)	(32,093)	(20,462)
Interest expense	8,027	7,716	24,283	22,762
Other income, net	(709)	(812)	(2,486)	(2,415)
Total expenses	(7,532)	(1,468)	(10,296)	(115)
(Loss) earnings before income taxes	(4,899)	(13,110)	(29,709)	(29,214)
Income tax benefit	(1,622)	(8,143)	(7,911)	(19,592)
Net (loss) earnings	(3,277)	(4,967)	(21,798)	(9,622)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	70,692	78,561	197,022	228,479
Expenses:
Direct expenses	51,247	61,750	155,434	185,148
Selling, general and administrative expenses	3,141	3,092	9,296	8,766
Total operating expenses	54,388	64,842	164,730	193,914
Gain (loss) on disposal of assets	0		(1)
Equity in loss of unconsolidated affiliate, net		0		0
Operating (loss) income	16,304	13,719	32,293	34,565
Interest expense	0	3	22	30
Other income, net	(1)	0	(2)	(4)
Total expenses	(1)	3	20	26
(Loss) earnings before income taxes	16,305	13,716	32,273	34,539
Income tax benefit	0	5,344	(1,413)	14,077
Net (loss) earnings	16,305	$ 8,372	33,686	$ 20,462
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	7,784		15,987
Expenses:
Direct expenses	9,765		16,920
Selling, general and administrative expenses	24		144
Total operating expenses	9,789		17,064
Gain (loss) on disposal of assets	0		0
Equity in loss of unconsolidated affiliate, net	(550)		516
Operating (loss) income	(1,455)		(1,593)
Interest expense	0		0
Other income, net	0		0
Total expenses	0		0
(Loss) earnings before income taxes	(1,455)		(1,593)
Income tax benefit	0
Net (loss) earnings	$ (1,455)		$ (1,593)