Condensed Consolidating Financial Information - Condensed Consolidating Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	$ 204,197		$ 197,071
Expenses:
Direct expenses	169,207		158,653
Selling, general and administrative expenses	11,237		9,328
Total operating expenses	180,444		167,981
Gain on disposal of assets, net	(7)		1,073
Equity in loss of unconsolidated affiliate	68		41
Operating income	23,692		27,976
Interest expense	7,170		7,364
Loss on debt extinguishment			29,216
Other income, net	(462)		(91)
Total expenses	6,708		36,489
Earnings (loss) before income taxes	16,984		(8,513)
Income tax expense (benefit)	6,621		(3,192)
Net earnings (loss)	10,363		(5,321)
Parent Company Only (issuer) [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	128,658		124,354
Expenses:
Direct expenses	106,481		96,426
Selling, general and administrative expenses	8,508		7,081
Management fees			(2,909)
Total operating expenses	114,989		100,598
Gain on disposal of assets, net	(7)		115
Equity in loss of unconsolidated affiliate	68		41
Operating income	13,608		23,600
Equity in net income of consolidated subsidiaries	(6,131)		(2,735)
Interest expense	7,170		7,364
Loss on debt extinguishment			29,216
Other income, net	(462)		(91)
Total expenses	577		33,754
Earnings (loss) before income taxes	13,031		(10,154)
Income tax expense (benefit)	2,668		(4,833)
Net earnings (loss)	10,363		(5,321)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues, net	75,539	[1]	72,717	[1]
Expenses:
Direct expenses	62,730	[1]	62,227	[1]
Selling, general and administrative expenses	2,729	[1]	2,247	[1]
Management fees			2,909	[1]
Total operating expenses	65,459	[1]	67,383	[1]
Gain on disposal of assets, net			958	[1]
Operating income	10,080	[1]	4,376	[1]
Other income, net	(4)	[1]
Total expenses	(4)	[1]
Earnings (loss) before income taxes	10,084	[1]	4,376	[1]
Income tax expense (benefit)	3,953	[1]	1,641	[1]
Net earnings (loss)	6,131	[1]	2,735	[1]
Eliminations [Member]
Expenses:
Direct expenses	(4)
Total operating expenses	(4)
Operating income	4
Equity in net income of consolidated subsidiaries	6,131		2,735
Other income, net	4
Total expenses	6,135		2,735
Earnings (loss) before income taxes	(6,131)		(2,735)
Net earnings (loss)	$ (6,131)		$ (2,735)

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