Unaudited Quarterly Financial Data - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 05, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 94,100	$ 6,198	$ 9,358	$ 18,406	$ 8,559	$ 36,206	$ 41,206	$ 56,961	$ 29,010
Restricted cash		7,901	5,867	5,020	4,701	7,648	8,441	29,910	10,421
Accounts receivable, net		261,400	260,438	266,660	278,064	270,812	253,986	262,260	238,680
Related party receivables		716	42	206		0
Inventories, net		19,047	16,996	16,735	16,321	16,220	16,122	15,088	13,519
Prepaid expenses and other current assets		23,663	22,617	23,713	25,252	24,937	26,933	24,108	27,520
Total current assets		318,925	315,318	330,740	332,897	355,823	346,688	388,327	319,150
Property, plant and equipment, net of accumulated depreciation of $154,060		113,637	119,469	125,018	129,621	132,986	131,156	135,585	132,870
Operating lease right-of-use assets, net		93,627	93,352	96,498	100,727
Goodwill		359,771	611,982	708,246	708,285	708,258	749,762	748,708	747,325	$ 747,325
Intangible assets, net		342,443	357,114	372,004	383,680	395,020	384,895	405,457	424,251
Deferred income tax assets		12,032	15,950	16,301	16,322	16,345	15,606	16,076	9,967
Other noncurrent assets		17,889	13,557	14,714	17,667	19,391	21,650	21,276	18,490
Total assets		1,258,324	1,526,742	1,663,521	1,689,199	1,627,823	1,649,757	1,715,429	1,652,053
Current liabilities
Accounts payables		86,167	93,815	99,089	90,924	99,853	90,673	86,304	77,194
Related party payables		1,740	10,207	11,671	13,812	15,363	15,792	17,023	14,172
Income tax payable		352		2,525	4,898	1,996	5,422	5,385	6,967
Accrued liabilities		121,553	104,097	102,265	105,018	107,355	81,259	79,851	70,217
Accrued compensation and benefits		48,574	49,636	50,218	55,745	52,211	52,464	48,409	47,279
Accrued interest		48,769	24,602	48,935	23,928	49,071	23,845	48,885	23,795
Customer deposits		27,765	30,161	28,914	28,410	34,235	39,419	36,997	36,542
Deferred revenue		16,282	17,368	19,428	19,966	16,504	18,084	20,654	15,933
Obligation for claim payment		39,156	43,267	41,496	46,063	56,002	52,889	94,233	56,554
Current portion of finance lease liabilities		13,788	15,172	15,897	15,961		15,926	16,568	14,785
Current portion of operating lease liabilities		25,345	26,604	27,444	27,368
Current portion of long-term debts		36,490	37,237	38,929	32,821	29,237	20,062	19,799	21,170
Total current liabilities		465,981	452,166	486,811	464,914	479,325	415,835	474,108	384,608
Long-term debt, net of current maturities		1,398,385	1,367,583	1,331,898	1,336,152	1,306,423	1,307,884	1,278,197	1,277,029
Finance lease liabilities, net of current portion		20,272	24,159	25,772	27,231		22,945	25,193	26,474
Pension liabilities		25,681	28,850	27,141	27,730	27,641	32,887	32,967	28,540
Deferred income tax liabilities		7,996	12,679	15,898	12,441	11,214	2,115	5,016	5,478
Long-term income tax liabilities		2,806	2,892	2,842	3,158	3,024	3,470	3,470	3,470
Operating lease liabilities, net of current portion		73,282	71,661	74,290	78,290
Other long-term liabilities		6,962	7,866	7,882	6,747	14,717	15,307	16,208	13,879
Total liabilities		2,001,365	1,967,856	1,972,534	1,956,663	1,869,082	1,800,443	1,835,159	1,739,478
Commitments and Contingencies (Note 14)
Stockholders' equity (deficit)
Common Stock		15	15	15	15	15	15	15	15
Preferred Stock		1	1	1	1	1	1	1	1
Additional paid in capital		445,452	445,452	445,452	445,452	445,452	445,452	445,452	445,452
Less: common stock held in treasury, at cost; 2,549,185 shares		(10,949)	(10,949)	(10,949)	(10,342)	(10,342)	(5,148)	(3,728)	(249)
Equity-based compensation		49,336	48,411	47,190	44,529	41,731	38,601	36,980	35,044
Accumulated deficit		(1,211,508)	(907,422)	(776,134)	(734,563)	(702,392)	(615,058)	(586,253)	(555,744)
Accumulated other comprehensive loss:
Foreign currency translation adjustment		(7,329)	(7,644)	(5,319)	(3,031)	(6,423)	(3,858)	(1,366)	(487)
Unrealized pension actuarial losses, net of tax		(8,059)	(8,978)	(9,269)	(9,525)	(9,301)	(10,691)	(10,831)	(11,457)
Total accumulated other comprehensive loss		(15,388)	(16,622)	(14,588)	(12,556)	(15,724)	(14,549)	(12,197)	(11,944)
Total stockholders’ deficit		(743,041)	(441,114)	(309,013)	(267,464)	(241,259)	(150,686)	(119,730)	(87,425)	$ (51,796)	$ (339,901)
Total liabilities and stockholders’ deficit		$ 1,258,324	1,526,742	1,663,521	1,689,199	1,627,823	1,649,757	1,715,429	1,652,053
As previously reported
Current assets
Cash and cash equivalents			10,312	18,449	8,262	25,615	40,692	55,783	26,882
Restricted cash			4,913	4,977	4,998	18,239	8,955	31,088	12,549
Accounts receivable, net			260,438	266,660	278,064	270,812	253,986	262,260	238,680
Related party receivables			42	206
Inventories, net			16,996	16,735	16,321	16,220	16,122	15,088	13,519
Prepaid expenses and other current assets			22,695	23,791	25,330	25,015	26,933	24,108	27,520
Total current assets			315,396	330,818	332,975	355,901	346,688	388,327	319,150
Property, plant and equipment, net of accumulated depreciation of $154,060			119,469	125,018	129,621	132,986	131,156	135,585	132,870
Operating lease right-of-use assets, net			93,352	96,498	100,727
Goodwill			609,458	708,246	708,285	708,258	749,762	748,708	747,325
Intangible assets, net			374,445	387,775	397,412	407,021	398,280	419,725	438,929
Deferred income tax assets			15,830	16,181	16,202	16,225	14,810	15,280	9,171
Other noncurrent assets			13,557	14,714	17,667	19,391	21,650	21,276	18,490
Total assets			1,541,507	1,679,250	1,702,889	1,639,782	1,662,346	1,728,901	1,665,935
Current liabilities
Accounts payables			93,815	99,089	90,924	99,853	90,673	86,304	77,194
Related party payables			274	238	6,184	7,735	10,756	11,987	14,172
Income tax payable				2,525	4,898	1,996	5,422	5,385	6,967
Accrued liabilities			60,994	59,487	63,138	66,008	41,397	40,737	31,805
Accrued compensation and benefits			51,819	52,493	57,961	54,583	54,975	50,905	49,738
Accrued interest			24,602	48,935	23,928	49,071	23,845	48,885	23,795
Customer deposits			30,161	28,914	28,410	34,235	39,419	36,997	36,542
Deferred revenue			17,368	19,428	19,966	16,504	18,084	20,654	15,933
Obligation for claim payment			43,267	41,496	46,063	56,002	52,889	94,233	56,554
Current portion of finance lease liabilities			15,172	15,897	15,961		15,926	16,568	14,785
Current portion of operating lease liabilities			26,604	27,444	27,368
Current portion of long-term debts			37,237	38,929	32,821	29,237	20,062	16,299	21,170
Total current liabilities			401,313	434,875	417,622	432,722	373,448	428,954	348,655
Long-term debt, net of current maturities			1,367,583	1,331,898	1,336,152	1,306,423	1,307,884	1,281,697	1,277,029
Finance lease liabilities, net of current portion			24,159	25,772	27,231		22,945	25,193	26,474
Pension liabilities			26,667	24,866	25,514	25,269	30,376	30,471	26,081
Deferred income tax liabilities			12,677	15,896	12,439	11,212	2,115	5,016	5,478
Long-term income tax liabilities			2,892	2,842	3,158	3,024	3,470	3,470	3,470
Operating lease liabilities, net of current portion			71,661	74,290	78,290
Other long-term liabilities			7,866	7,882	6,747	15,400	15,307	16,208	13,879
Total liabilities			1,914,818	1,918,321	1,907,153	1,820,788	1,755,545	1,791,009	1,701,066
Commitments and Contingencies (Note 14)
Stockholders' equity (deficit)
Common Stock			15	15	15	15	15	15	15
Preferred Stock			1	1	1	1	1	1	1
Additional paid in capital			482,018	482,018	482,018	482,018	482,018	482,018	482,018
Less: common stock held in treasury, at cost; 2,549,185 shares			(10,949)	(10,949)	(10,342)	(10,342)	(5,148)	(3,728)	(249)
Equity-based compensation			48,411	47,190	44,529	41,731	38,601	36,980	35,044
Accumulated deficit			(876,043)	(742,616)	(707,787)	(678,563)	(594,162)	(565,222)	(540,041)
Accumulated other comprehensive loss:
Foreign currency translation adjustment			(7,786)	(5,461)	(3,173)	(6,565)	(3,833)	(1,341)	(462)
Unrealized pension actuarial losses, net of tax			(8,978)	(9,269)	(9,525)	(9,301)	(10,691)	(10,831)	(11,457)
Total accumulated other comprehensive loss			(16,764)	(14,730)	(12,698)	(15,866)	(14,524)	(12,172)	(11,919)
Total stockholders’ deficit			(373,311)	(239,071)	(204,264)	(181,006)	(93,199)	(62,108)	(35,131)
Total liabilities and stockholders’ deficit			1,541,507	1,679,250	1,702,889	1,639,782	1,662,346	1,728,901	1,665,935
Adjustment
Current assets
Cash and cash equivalents			(954)	(43)	297	10,591	514	1,178	2,128
Restricted cash			954	43	(297)	(10,591)	(514)	(1,178)	(2,128)
Prepaid expenses and other current assets			(78)	(78)	(78)	(78)
Total current assets			(78)	(78)	(78)	(78)
Goodwill			2,524
Intangible assets, net			(17,331)	(15,771)	(13,732)	(12,001)	(13,385)	(14,268)	(14,678)
Deferred income tax assets			120	120	120	120	796	796	796
Total assets			(14,765)	(15,729)	(13,690)	(11,959)	(12,589)	(13,472)	(13,882)
Current liabilities
Related party payables			9,933	11,433	7,628	7,628	5,036	5,036
Accrued liabilities			43,103	42,778	41,880	41,347	39,862	39,114	38,412
Accrued compensation and benefits			(2,183)	(2,275)	(2,216)	(2,372)	(2,511)	(2,496)	(2,459)
Current portion of long-term debts								3,500
Total current liabilities			50,853	51,936	47,292	46,603	42,387	45,154	35,953
Long-term debt, net of current maturities								(3,500)
Pension liabilities			2,183	2,275	2,216	2,372	2,511	2,496	2,459
Deferred income tax liabilities			2	2	2	2
Other long-term liabilities						(683)
Total liabilities			53,038	54,213	49,510	48,294	44,898	44,150	38,412
Commitments and Contingencies (Note 14)
Stockholders' equity (deficit)
Additional paid in capital			(36,566)	(36,566)	(36,566)	(36,566)	(36,566)	(36,566)	(36,566)
Accumulated deficit			(31,379)	(33,518)	(26,776)	(23,829)	(20,896)	(21,031)	(15,703)
Accumulated other comprehensive loss:
Foreign currency translation adjustment			142	142	142	142	(25)	(25)	(25)
Total accumulated other comprehensive loss			142	142	142	142	(25)	(25)	(25)
Total stockholders’ deficit			(67,803)	(69,942)	(63,200)	(60,253)	(57,487)	(57,622)	(52,294)
Total liabilities and stockholders’ deficit			$ (14,765)	$ (15,729)	$ (13,690)	$ (11,959)	$ (12,589)	$ (13,472)	$ (13,882)