Condensed Consolidating Financial Information - Guarantor Subsidiaries - Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	$ 176,023	$ 168,787	$ 169,243	$ 160,370	$ 148,336	$ 150,167	$ 146,424	$ 134,618	$ 674,423	$ 579,545	$ 634,098
Expenses:
Direct expenses									631,807	546,699	592,550
Selling, general, and administrative expenses									66,685	53,817	44,418
Total operating expenses									698,492	600,516	636,968
Loss (gain) on disposition of assets, net	(45)	0	171	(879)	(287)	(4)	(7)	0	753	298	(3,350)
Impairment of assets									109,024	368	407
Equity in profit (loss) of unconsolidated affiliate									(188)	385	(151)
Operating (loss) income									(133,658)	(22,022)	224
Interest expense									33,981	32,183	30,644
Other income, net									(179)	(2,764)	(3,271)
Total expenses									33,802	29,419	27,373
(Loss) earnings before income taxes	(123,148)	(14,062)	(8,777)	(21,473)	(20,319)	(4,899)	(3,150)	(23,073)	(167,460)	(51,441)	(27,149)
Income tax (benefit) expense									(25,946)	(58,973)	(469)
Net earnings (loss)	$ (105,907)	$ (11,531)	$ (7,093)	$ (16,983)	$ 29,330	$ (3,277)	$ (3,273)	$ (15,248)	(141,514)	7,532	(26,680)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net									(28,406)	(17,004)
Expenses:
Direct expenses									(28,406)	(17,004)
Selling, general, and administrative expenses									(18)		(18)
Total operating expenses									(28,424)	(17,004)	(18)
Operating (loss) income									18	0	18
Equity in net earnings of consolidated subsidiaries									(56,786)	38,553	22,182
Other income, net									18		18
Total expenses									(56,768)	38,553	22,200
(Loss) earnings before income taxes									56,786	(38,553)	(22,182)
Net earnings (loss)									56,786	(38,553)	(22,182)
Reportable Legal Entities [Member] | Parent Company Only (issuer) [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net									329,268	310,449	339,829
Expenses:
Direct expenses									331,785	326,152	347,532
Selling, general, and administrative expenses									40,715	41,134	32,911
Total operating expenses									372,500	367,286	380,443
Loss (gain) on disposition of assets, net									774	300	(3,350)
Impairment of assets									31,824	368
Equity in profit (loss) of unconsolidated affiliate									(188)	1,021	(151)
Operating (loss) income									(75,642)	(58,526)	(37,520)
Equity in net earnings of consolidated subsidiaries									56,786	(38,553)	(22,182)
Interest expense									33,964	32,161	30,585
Other income, net									(547)	(2,757)	(3,284)
Total expenses									90,203	(9,149)	5,119
(Loss) earnings before income taxes									(165,845)	(49,377)	(42,639)
Income tax (benefit) expense									(24,331)	(56,909)	(15,959)
Net earnings (loss)									(141,514)	7,532	(26,680)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net									263,679	262,229	293,329
Expenses:
Direct expenses									236,366	212,691	237,635
Selling, general, and administrative expenses									13,834	12,462	10,984
Total operating expenses									250,200	225,153	248,619
Loss (gain) on disposition of assets, net										(2)
Operating (loss) income									13,479	37,078	44,710
Interest expense									13	22	46
Other income, net										(2)	(5)
Total expenses									13	20	41
(Loss) earnings before income taxes									13,466	37,058	44,669
Income tax (benefit) expense									1,785	(1,138)	15,490
Net earnings (loss)									11,681	38,196	29,179
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net									109,882	23,871	940
Expenses:
Direct expenses									92,062	24,860	7,383
Selling, general, and administrative expenses									12,154	221	541
Total operating expenses									104,216	25,081	7,924
Loss (gain) on disposition of assets, net									(21)
Impairment of assets									77,200
Equity in profit (loss) of unconsolidated affiliate										(636)
Operating (loss) income									(71,513)	(574)	(6,984)
Interest expense									4		13
Other income, net									350	(5)
Total expenses									354	(5)	13
(Loss) earnings before income taxes									(71,867)	(569)	(6,997)
Income tax (benefit) expense									(3,400)	(926)
Net earnings (loss)									$ (68,467)	$ 357	$ (6,997)