RESTATEMENT OF PREVIOUSLY ISSUED CONSOLIDATED FINANCIAL STATEMENTS - INCOME AND COMPREHENSIVE INCOME (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revision of Previously Reported Consolidated Financial Information
Net revenue	$ 278,910	$ 261,699	$ 255,574	$ 215,917	$ 255,048	$ 253,217	$ 253,667	$ 213,837	$ 471,491	$ 467,504	$ 733,190	$ 720,721	$ 1,012,100	$ 975,769	$ 923,521
Material costs	86,365	86,238	81,109	70,572	77,831	78,933	77,273	67,966	151,681	145,239	237,919	224,172	324,284	302,003	285,873
Personnel costs	93,516	89,104	88,738	82,228	83,742	82,071	82,836	77,131	170,966	159,967	260,070	242,038	353,586	325,780	299,004
Other operating costs	35,636	34,621	34,291	32,337	27,398	28,526	28,620	31,223	66,628	59,843	101,249	88,369	136,885	115,767	110,881
General and administrative expenses	22,383	21,794	22,545	19,616	21,841	19,137	21,204	16,476	42,161	37,680	63,955	56,817	86,338	78,658	81,182
Professional accounting and legal fees	19,768	20,973	2,600	1,457	1,205	1,715	1,501	1,400	4,057	2,901	25,030	4,616	44,798	5,821	4,907
Depreciation and amortization	9,978	9,818	9,826	9,307	8,487	8,526	8,805	8,367	19,133	17,172	28,951	25,698	38,929	34,185	32,589
Income from operations	11,264	(849)	16,465	400	34,544	34,309	33,428	11,274	16,865	44,702	16,016	79,011	27,280	113,555	109,085
Interest expense, net	7,191	7,255	7,063	6,768	6,372	6,942	8,616	8,646	13,831	17,262	21,086	24,204	28,277	30,576	34,620
Extinguishment of debt							6,645			6,645		6,645		6,645
(Loss) income from continuing operations before income taxes	4,073	(8,104)	9,402	(6,368)	28,172	27,367	18,167	2,628	3,034	20,795	(5,070)	48,162	(997)	76,334	74,465
Provision for income taxes	1,267	(10,054)	10,832	(22)	13,077	9,815	6,688	875	10,810	7,563	756	17,378	2,023	30,455	26,206
(Loss) income from continuing operations	2,806	1,950	(1,430)	(6,346)	15,095	17,552	11,479	1,753	(7,776)	13,232	(5,826)	30,784	(3,020)	45,879	48,259
Loss from discontinued operations, net of income taxes	(6,235)	(10,751)	4,661	(3,621)	(3,063)	(2,034)	(282)	11	1,040	(271)	(9,711)	(2,305)	(15,946)	(5,368)	(235)
Net (loss) income	(3,429)	(8,801)	3,231	(9,967)	12,032	15,518	11,197	1,764	(6,736)	12,961	(15,537)	28,479	(18,966)	40,511	48,024
Other comprehensive (loss) income:
Unrealized gain (loss) on SERP, net of income tax provision (benefit)	(868)				899								(868)	899	(734)
Unrealized (loss) gain on SERP, tax (benefit) provision	525				531								(525)	531	(439)
Total other comprehensive (loss) income	(868)				899								(868)	899	(734)
Comprehensive (loss) income	$ (4,297)	$ (8,801)	$ 3,231	$ (9,967)	$ 12,931	$ 15,518	$ 11,197	$ 1,764	$ (6,736)	$ 12,961	$ (15,537)	$ 28,479	$ (19,834)	$ 41,410	$ 47,290
Basic Per Common Share Data
Net income from continuing operations (in dollars per share)	$ 0.08	$ 0.05	$ (0.04)	$ (0.18)	$ 0.43	$ 0.50	$ 0.33	$ 0.05	$ (0.22)	$ 0.38	$ (0.17)	$ 0.89	$ (0.09)	$ 1.32	$ 1.41
Loss from discontinued operations, net of income taxes	(0.18)	(0.30)	0.13	(0.10)	(0.09)	(0.06)	(0.01)		0.03	(0.01)	(0.27)	(0.07)	(0.45)	(0.16)	(0.01)
Basic (loss) income per share (in dollars per share)	$ (0.10)	$ (0.25)	$ 0.09	$ (0.28)	$ 0.34	$ 0.44	$ 0.32	$ 0.05	$ (0.19)	$ 0.37	$ (0.44)	$ 0.82	$ (0.54)	$ 1.16	$ 1.40
Shares used to compute basic per common share amounts (in shares)	35,397,195	35,388,862	35,377,939	35,056,902	34,945,120	34,927,373	34,872,430	34,570,836	35,209,849	34,710,269	35,275,046	34,782,207	35,309,478	34,825,867	34,273,621
Diluted Per Common Share Data
Net income from continuing operations (in dollars per share)	$ 0.08	$ 0.05	$ (0.04)	$ (0.18)	$ 0.43	$ 0.50	$ 0.33	$ 0.05	$ (0.22)	$ 0.38	$ (0.17)	$ 0.88	$ (0.09)	$ 1.30	$ 1.39
Loss from discontinued operations, net of income taxes	(0.18)	(0.30)	0.13	(0.10)	(0.09)	(0.06)	(0.01)		0.03	(0.01)	(0.27)	(0.07)	(0.45)	(0.15)	(0.01)
Diluted (loss) income per share (in dollars per share)	$ (0.10)	$ (0.25)	$ 0.09	$ (0.28)	$ 0.34	$ 0.44	$ 0.32	$ 0.05	$ (0.19)	$ 0.37	$ (0.44)	$ 0.81	$ (0.54)	$ 1.15	$ 1.38
Shares used to compute diluted per common share amounts (in shares)	35,615,092	35,571,188	35,377,939	35,056,902	35,364,729	35,298,046	35,211,878	35,062,115	35,209,849	35,124,223	35,275,046	35,180,990	35,309,478	35,208,754	34,737,420
As Previously Reported
Revision of Previously Reported Consolidated Financial Information
Net revenue			$ 275,854	$ 235,605	$ 278,237	$ 271,053	$ 267,798	$ 229,350	$ 511,459	$ 497,148		$ 768,201		$ 1,046,438	$ 974,429
Material costs			81,822	67,345	92,461	79,401	79,446	67,739	149,167	147,184		226,585		319,046	296,193
Personnel costs			102,755	96,431	91,841	94,768	93,176	89,953	199,186	183,129		277,897		369,738	335,328
Other operating costs			52,741	45,600	49,870	47,754	49,022	39,657	98,341	88,680		136,434		186,304	178,918
Depreciation and amortization			12,133	10,199	9,467	9,224	9,510	9,285	22,332	18,795		28,019		37,486	34,652
Income from operations			26,403	16,030	34,598	39,906	36,644	22,716	42,433	59,360		99,266		133,864	129,338
Interest expense, net			6,201	6,098	4,973	6,017	7,708	7,777	12,299	15,485		21,502		26,475	31,169
Extinguishment of debt							6,645			6,645		6,645		6,645
(Loss) income from continuing operations before income taxes			20,202	9,932	29,625	33,889	22,291	14,939	30,134	37,230		71,119		100,744	98,169
Provision for income taxes			7,583	3,935	11,269	12,230	8,212	5,449	11,518	13,661		25,891		37,160	34,477
(Loss) income from continuing operations			12,619	5,997	18,356	21,659	14,079	9,490	18,616	23,569		45,228		63,584	63,692
Net (loss) income			12,619	5,997	18,356	21,659	14,079	9,490	18,616	23,569		45,228		63,584	63,692
Other comprehensive (loss) income:
Unrealized gain (loss) on SERP, net of income tax provision (benefit)					899									899	(734)
Total other comprehensive (loss) income					899									899	(734)
Comprehensive (loss) income			$ 12,619	$ 5,997	$ 19,255	$ 21,659	$ 14,079	$ 9,490	$ 18,616	$ 23,569		$ 45,228		$ 64,483	$ 62,958
Basic Per Common Share Data
Net income from continuing operations (in dollars per share)			$ 0.36	$ 0.17	$ 0.53	$ 0.62	$ 0.40	$ 0.27	$ 0.53	$ 0.68		$ 1.30		$ 1.83	$ 1.86
Basic (loss) income per share (in dollars per share)			$ 0.36	$ 0.17	$ 0.53	$ 0.62	$ 0.40	$ 0.27	$ 0.53	$ 0.68		$ 1.30		$ 1.83	$ 1.86
Shares used to compute basic per common share amounts (in shares)			35,469,769	35,076,828	34,922,599	34,902,103	34,849,659	34,598,494	35,319,944	34,724,077		34,783,419		34,818,214	34,282,591
Diluted Per Common Share Data
Net income from continuing operations (in dollars per share)			$ 0.35	$ 0.17	$ 0.52	$ 0.61	$ 0.40	$ 0.27	$ 0.52	$ 0.67		$ 1.28		$ 1.80	$ 1.83
Diluted (loss) income per share (in dollars per share)			$ 0.35	$ 0.17	$ 0.52	$ 0.61	$ 0.40	$ 0.27	$ 0.52	$ 0.67		$ 1.28		$ 1.80	$ 1.83
Shares used to compute diluted per common share amounts (in shares)			35,591,764	35,415,018	35,463,539	35,401,273	35,307,697	35,066,032	35,470,170	35,225,871		35,315,897		35,394,721	34,832,830
Restatement Adjustments (excluding reclassification adjustments and discontinued operations)
Revision of Previously Reported Consolidated Financial Information
Net revenue			$ (8,794)	$ (9,134)	$ (12,049)	$ (8,383)	$ (2,963)	$ (4,581)	$ (17,928)	$ (7,544)		$ (15,927)		$ (27,976)	$ (11,629)
Material costs			3,855	8,016	(8,949)	3,417	2,023	4,247	11,871	6,271		9,688		738	2,686
Personnel costs			1,712	2,679	6,673	(552)	1,462	1,681	4,391	3,143		2,591		9,264	9,255
Other operating costs			688	485	(4,185)	(2,015)	(2,452)	1,475	1,173	(978)		(2,993)		(7,178)	(2,047)
Depreciation and amortization			(1,898)	(483)	(580)	(317)	(344)	(578)	(2,381)	(922)		(1,239)		(1,819)	(1,044)
Income from operations			(13,151)	(19,831)	(5,008)	(8,916)	(3,652)	(11,406)	(32,982)	(15,058)		(23,974)		(28,981)	(20,479)
Interest expense, net			892	667	1,411	932	926	884	1,559	1,810		2,742		4,154	3,540
(Loss) income from continuing operations before income taxes			(14,043)	(20,498)	(6,419)	(9,848)	(4,578)	(12,290)	(34,541)	(16,868)		(26,716)		(33,135)	(24,019)
Provision for income taxes			(4,655)	(4,534)	(95)	(3,707)	(1,696)	(4,564)	(9,189)	(6,260)		(9,967)		(10,062)	(8,351)
(Loss) income from continuing operations			(9,388)	(15,964)	(6,324)	(6,141)	(2,882)	(7,726)	(25,352)	(10,608)		(16,749)		(23,073)	(15,668)
Net (loss) income			(9,388)	(15,964)	(6,324)	(6,141)	(2,882)	(7,726)	(25,352)	(10,608)		(16,749)		(23,073)	(15,668)
Other comprehensive (loss) income:
Comprehensive (loss) income			$ (9,388)	$ (15,964)	$ (6,324)	$ (6,141)	$ (2,882)	$ (7,726)	$ (25,352)	$ (10,608)		$ (16,749)		$ (23,073)	$ (15,668)
Basic Per Common Share Data
Net income from continuing operations (in dollars per share)			$ (0.27)	$ (0.45)	$ (0.19)	$ (0.18)	$ (0.08)	$ (0.22)	$ (0.72)	$ (0.31)		$ (0.48)		$ (0.67)	$ (0.46)
Basic (loss) income per share (in dollars per share)			$ (0.27)	$ (0.45)	$ (0.19)	$ (0.18)	$ (0.08)	$ (0.22)	$ (0.72)	$ (0.31)		$ (0.48)		$ (0.67)	$ (0.46)
Shares used to compute basic per common share amounts (in shares)			(91,830)	(19,926)	22,521	25,270	22,771	(27,658)	(110,095)	(13,808)		(1,212)		7,653	(8,970)
Diluted Per Common Share Data
Net income from continuing operations (in dollars per share)			$ (0.26)	$ (0.45)	$ (0.18)	$ (0.17)	$ (0.08)	$ (0.22)	$ (0.71)	$ (0.30)		$ (0.47)		$ (0.65)	$ (0.45)
Diluted (loss) income per share (in dollars per share)			$ (0.26)	$ (0.45)	$ (0.18)	$ (0.17)	$ (0.08)	$ (0.22)	$ (0.71)	$ (0.30)		$ (0.47)		$ (0.65)	$ (0.45)
Shares used to compute diluted per common share amounts (in shares)			(213,825)	(358,116)	(98,810)	(103,227)	(95,819)	(3,917)	(260,321)	(101,648)		(134,907)		(185,967)	(95,410)
Restatement Adjustments
Revision of Previously Reported Consolidated Financial Information
Depreciation and amortization				$ (892)				$ (918)	$ (3,199)	$ (1,623)		$ (2,321)		$ (3,301)	$ (2,063)
Extinguishment of debt										6,645		6,645
(Loss) income from continuing operations				(12,343)				(7,737)	(26,392)	(10,337)		(14,444)		(17,705)	(15,433)
Loss from discontinued operations, net of income taxes				(3,621)				11	1,040	(271)		(2,305)		(5,368)	(235)
Net (loss) income				(15,964)				(7,726)	(25,352)	(10,608)		(16,749)		(23,073)	(15,668)
Reclassification Adjustment
Revision of Previously Reported Consolidated Financial Information
Personnel costs														(31,805)	(27,133)
Other operating costs														(52,674)	(58,956)
General and administrative expenses														78,658	81,182
Professional accounting and legal fees														5,821	4,907
Discontinued Operations
Revision of Previously Reported Consolidated Financial Information
Net revenue			$ (11,486)	(10,554)	$ (11,140)	$ (9,453)	$ (11,168)	(10,932)	(22,040)	(22,100)		(31,553)		(42,693)	(39,279)
Material costs			(4,568)	(4,789)	(5,681)	(3,885)	(4,196)	(4,020)	(9,357)	(8,216)		(12,101)		(17,781)	(13,006)
Personnel costs			(5,712)	(5,836)	(5,911)	(5,370)	(5,198)	(4,938)	(11,548)	(10,136)		(15,506)		(21,417)	(18,446)
Other operating costs			(4,010)	(3,721)	(4,102)	(3,136)	(1,849)	(1,598)	(7,731)	(3,447)		(6,583)		(10,685)	(7,034)
Depreciation and amortization			(409)	(409)	(400)	(381)	(361)	(340)	(818)	(701)		(1,082)		(1,482)	(1,019)
Income from operations			3,213	4,201	4,954	3,319	436	(36)	7,414	400		3,719		8,672	226
Interest expense, net			(30)	3	(12)	(7)	(18)	(15)	(27)	(33)		(40)		(53)	(89)
(Loss) income from continuing operations before income taxes			3,243	4,198	4,966	3,326	454	(21)	7,441	433		3,759		8,725	315
Provision for income taxes			7,904	577	1,903	1,292	172	(10)	8,481	162		1,454		3,357	80
(Loss) income from continuing operations			(4,661)	3,621	3,063	2,034	282	(11)	(1,040)	271		2,305		5,368	235
Loss from discontinued operations, net of income taxes			$ 4,661	$ (3,621)	$ (3,063)	$ (2,034)	$ (282)	$ 11	$ 1,040	$ (271)		$ (2,305)		$ (5,368)	$ (235)
Basic Per Common Share Data
Net income from continuing operations (in dollars per share)			$ (0.13)	$ 0.10	$ 0.09	$ 0.06	$ 0.01		$ (0.03)	$ 0.01		$ 0.07		$ 0.16	$ 0.01
Loss from discontinued operations, net of income taxes			0.13	(0.10)	(0.09)	(0.06)	(0.01)		0.03	(0.01)		(0.07)		(0.16)	(0.01)
Diluted Per Common Share Data
Net income from continuing operations (in dollars per share)			(0.13)	0.10	0.09	0.06	0.01		(0.03)	0.01		0.07		0.15	0.01
Loss from discontinued operations, net of income taxes			$ 0.13	$ (0.10)	$ (0.09)	$ (0.06)	$ (0.01)		$ 0.03	$ (0.01)		$ (0.07)		$ (0.15)	$ (0.01)