Description of the Business and Basis of Presentation - Schedule of Impact of Corrections on Affected Condensed Consolidated Statements of Comprehensive Income Line Items (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended					9 Months Ended	12 Months Ended			3 Months Ended					9 Months Ended	12 Months Ended			3 Months Ended					9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014 As Previously Reported [Member]	Mar. 31, 2014 As Previously Reported [Member]	Sep. 30, 2013 As Previously Reported [Member]	Jun. 30, 2013 As Previously Reported [Member]	Mar. 31, 2013 As Previously Reported [Member]	Sep. 30, 2013 As Previously Reported [Member]	Dec. 31, 2013 As Previously Reported [Member]	Dec. 31, 2012 As Previously Reported [Member]	Dec. 31, 2011 As Previously Reported [Member]	Jun. 30, 2014 Adjustments [Member]	Mar. 31, 2014 Adjustments [Member]	Sep. 30, 2013 Adjustments [Member]	Jun. 30, 2013 Adjustments [Member]	Mar. 31, 2013 Adjustments [Member]	Sep. 30, 2013 Adjustments [Member]	Dec. 31, 2013 Adjustments [Member]	Dec. 31, 2012 Adjustments [Member]	Dec. 31, 2011 Adjustments [Member]	Jun. 30, 2014 Scenario As Revised [Member]	Mar. 31, 2014 Scenario As Revised [Member]	Sep. 30, 2013 Scenario As Revised [Member]	Jun. 30, 2013 Scenario As Revised [Member]	Mar. 31, 2013 Scenario As Revised [Member]	Sep. 30, 2013 Scenario As Revised [Member]	Dec. 31, 2013 Scenario As Revised [Member]	Dec. 31, 2012 Scenario As Revised [Member]	Dec. 31, 2011 Scenario As Revised [Member]
Selected Statements of Comprehensive Income (Loss) Data:
Operating expenses	$ 200,891	$ 202,625	$ 557,993	$ 573,892	$ 189,190		$ 202,625	$ 194,674		$ 570,559	$ 739,989	$ 726,509	$ 687,999				$ 3,333		$ 3,333	$ 3,333	$ 4,073	$ 4,326	$ 189,190		$ 202,625	$ 198,007		$ 573,892	$ 743,322	$ 730,582	$ 692,325
Interest expense	20,857	20,211	61,087	70,439	20,638	20,046	21,018	22,926	28,606	72,550	93,536	111,426	110,097	(112)	(342)	(807)	(694)	(610)	(2,111)	(2,914)	(861)	(12,356)	20,526	19,704	20,211	22,232	27,996	70,439	90,622	110,565	97,741
Loss on early extinguishment of debt and write-off of discounts and deferred financing costs								32,429		32,429	32,429						(2,571)		(2,571)	(2,571)	2,053	15,129				29,858		29,858	29,858	2,053	15,129
Income (loss) before income taxes	140,653	185,396	121,630	97,264	59,994	(79,471)	184,589	(24,268)	(64,406)	95,915	75,482	116,926	32,541	112	342	807	(68)	610	1,349	2,152	(5,265)	(7,099)	60,106	(79,129)	185,396	(24,336)	(63,796)	97,264	77,634	111,661	25,442
Provision for (benefit from) income taxes	53,477	64,656	46,265	32,375	22,658	(30,040)	64,390	(8,414)	(24,046)	31,930	25,004	39,482	13,428	42	128	266	(22)	201	445	710	(2,042)	(2,775)	22,700	(29,912)	64,656	(8,436)	(23,845)	32,375	25,714	37,440	10,653
Net income (loss)	$ 87,176	$ 120,740	$ 75,365	$ 64,889	$ 37,336	$ (49,431)	$ 120,199	$ (15,854)	$ (40,360)	$ 63,985	$ 50,478	$ 77,444	$ 19,113	$ 70	$ 214	$ 541	$ (46)	$ 409	$ 904	$ 1,442	$ (3,223)	$ (4,324)	$ 37,406	$ (49,217)	$ 120,740	$ (15,900)	$ (39,951)	$ 64,889	$ 51,920	$ 74,221	$ 14,789
Earnings (loss) per share:
Net income (loss) per share, basic	$ 1.01	$ 1.35	$ 0.86	$ 0.75	$ 0.43	$ (0.56)	$ 1.34	$ (0.18)	$ (0.49)	$ 0.74	$ 0.58	$ 0.94	$ 0.23			$ 0.01		$ 0.01	$ 0.01	$ 0.01	$ (0.04)	$ (0.05)	$ 0.43	$ (0.56)	$ 1.35	$ (0.18)	$ (0.48)	$ 0.75	$ 0.59	$ 0.90	$ 0.18
Net income (loss) per share, diluted	$ 1.00	$ 1.34	$ 0.86	$ 0.74	$ 0.43	$ (0.56)	$ 1.33	$ (0.18)	$ (0.49)	$ 0.73	$ 0.57	$ 0.93	$ 0.23			$ 0.01		$ 0.01	$ 0.01	$ 0.02	$ (0.04)	$ (0.05)	$ 0.43	$ (0.56)	$ 1.34	$ (0.18)	$ (0.48)	$ 0.74	$ 0.59	$ 0.89	$ 0.18