Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Financial Statements, Captions [Line Items]
REVENUES	$ 408,474	$ 421,466	$ 1,223,390	$ 1,263,194
EXPENSES:
Operating	282,712	301,489	857,702	903,712
General and administrative	27,635	23,570	79,586	80,162
Depreciation and amortization	28,277	28,151	85,413	83,203
Asset impairments		985	2,238	985
Costs and Expenses	338,624	354,195	1,024,939	1,068,062
OPERATING INCOME	69,850	67,271	198,451	195,132
OTHER (INCOME) EXPENSE:
Interest expense, net	10,376	10,378	29,088	34,856
Expenses associated with debt refinancing transactions				36,528
Other (income) expense	(143)	(184)	(1,143)	(120)
Total non-operating expense (income)	10,233	10,194	27,945	71,264
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	59,617	57,077	170,506	123,868
Income tax benefit (expense)	(2,071)	(4,571)	(5,490)	133,253
Income from continuing operations	57,546	52,506	165,016	257,121
Loss from discontinued operations, net of taxes		(663)		(3,757)
NET INCOME	57,546	51,843	165,016	253,364
Parent
Condensed Financial Statements, Captions [Line Items]
REVENUES	319,127	312,837	939,686	945,213
EXPENSES:
Operating	226,820	232,380	671,914	704,221
General and administrative	8,719	6,954	25,648	24,649
Depreciation and amortization	20,389	19,268	60,266	56,855
Asset impairments			2,238
Costs and Expenses	255,928	258,602	760,066	785,725
OPERATING INCOME	63,199	54,235	179,620	159,488
OTHER (INCOME) EXPENSE:
Interest expense, net	8,821	8,877	26,232	29,593
Expenses associated with debt refinancing transactions				28,563
Other (income) expense	250	(275)	87	45
Total non-operating expense (income)	9,071	8,602	26,319	58,201
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	54,128	45,633	153,301	101,287
Income tax benefit (expense)	(208)	(217)	(342)	137,981
Income from continuing operations	53,920	45,416	152,959	239,268
Income from equity in subsidiaries	3,626	6,427	12,057	14,096
NET INCOME	57,546	51,843	165,016	253,364
Combined Subsidiary Guarantors
Condensed Financial Statements, Captions [Line Items]
REVENUES	310,597	337,548	936,352	1,007,279
EXPENSES:
Operating	277,142	298,028	838,436	888,789
General and administrative	18,916	16,616	53,938	55,513
Depreciation and amortization	7,888	8,883	25,147	26,348
Asset impairments		985		985
Costs and Expenses	303,946	324,512	917,521	971,635
OPERATING INCOME	6,651	13,036	18,831	35,644
OTHER (INCOME) EXPENSE:
Interest expense, net	1,555	1,501	2,856	5,263
Expenses associated with debt refinancing transactions				7,965
Other (income) expense	(61)	111	(589)	(107)
Total non-operating expense (income)	1,494	1,612	2,267	13,121
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	5,157	11,424	16,564	22,523
Income tax benefit (expense)	(1,863)	(4,354)	(5,148)	(4,728)
Income from continuing operations	3,294	7,070	11,416	17,795
Loss from discontinued operations, net of taxes		(663)		(3,757)
NET INCOME	3,294	6,407	11,416	14,038
Consolidating Adjustments and Other
Condensed Financial Statements, Captions [Line Items]
REVENUES	(221,250)	(228,919)	(652,648)	(689,298)
EXPENSES:
Operating	(221,250)	(228,919)	(652,648)	(689,298)
Costs and Expenses	(221,250)	(228,919)	(652,648)	(689,298)
OTHER (INCOME) EXPENSE:
Other (income) expense	(332)	(20)	(641)	(58)
Total non-operating expense (income)	(332)	(20)	(641)	(58)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	332	20	641	58
Income from continuing operations	332	20	641	58
Income from equity in subsidiaries	(3,626)	(6,427)	(12,057)	(14,096)
NET INCOME	$ (3,294)	$ (6,407)	$ (11,416)	$ (14,038)