Unaudited Quarterly Financial Data - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in pension liabilities	$ 25,681	$ 28,850	$ 27,141	$ 27,730	$ 27,641	$ 32,887	$ 32,967	$ 28,540	$ 27,141	$ 32,967	$ 28,850	$ 32,887	$ 25,681	$ 27,641
Increase in long term debt current	36,490	37,237	38,929	32,821	29,237	20,062	19,799	21,170	38,929	19,799	37,237	20,062	36,490	29,237
Decrease in long term debt non current	1,398,385	1,367,583	1,331,898	1,336,152	1,306,423	1,307,884	1,278,197	1,277,029	1,331,898	1,278,197	1,367,583	1,307,884	1,398,385	1,306,423
Goodwill	359,771	611,982	708,246	708,285	708,258	749,762	748,708	747,325	708,246	748,708	611,982	749,762	359,771	708,258	$ 747,325
Additions to outsource contract costs				2,434				492	2,860	1,377	3,130	2,360	1,285	4,009	10,992
Depreciation and amortization	24,421	25,079	24,779	26,624	33,684	33,410	34,744	36,239	51,403	70,982	76,482	104,393	100,903	138,077	98,890
Increase in revenue	393,586	373,545	390,849	404,357	399,643	383,030	410,382	393,167	795,206	803,549	1,168,751	1,186,579	1,562,337	1,586,222	1,145,891
Cost of revenue	314,858	295,445	303,831	310,601	306,654	296,685	315,167	294,897	614,432	610,064	909,877	906,749	1,224,735	1,213,403	827,544
Related party expense	1,742	1,430	5,331	998	3,664	775	6,783	1,181	6,329	7,964	7,759	8,739	9,501	12,403	33,431
Decrease to selling, general and administrative expense	49,678	48,347	51,162	49,677	48,114	44,897	46,378	45,519	100,839	91,897	149,186	136,794	198,864	184,908	220,955
Increase in sundry expense (income), net	(600)	165	(1,311)	2,715	905	(2,283)	(2,122)	229	1,404	(1,893)	1,569	(4,176)	(969)	3,271	(2,295)
Decrease to other expense (loss)	$ (10,003)	(406)	(2,527)	(1,493)	(2,567)	1,069	907	3,621	(4,020)	4,528	(4,424)	5,597	(14,429)	3,030	1,297
Foreign currency translation adjustments		(2,325)	(2,288)	3,392	(2,566)	(2,492)	(879)	(268)	1,104	(1,147)	(1,221)	(3,639)	(906)	(6,204)	3,328
Increase/ (decrease) to net cash flows provided operating activities				(42,648)				(21,653)	(14,838)	44,612	(47,357)	(7,391)	(63,851)	23,600	51,777
Increase/ (decrease) to net cash flows provided investing activities				(7,444)				(7,047)	(18,059)	(15,490)	(20,511)	(22,575)	(25,182)	(58,752)	(441,382)
Increase of borrowings of other loans				6,904				1,863	14,092	2,152	21,530	3,068	39,153	11,557	3,116
Cashflows provided by financing activities				19,530				(13,413)	12,358	(23,330)	39,268	(1,321)	59,139	(2,605)	436,413
Decrease in third party debt modification									1,049		1,049	103	1,049	103	34,459
Principal repayment on other loans				10,498				2,947	21,248	6,043	32,996	9,053	53,678	12,651	27,955
Cash paid for debt issuance costs									7		7	130	7	130	38,784
Reductions													$ 348,557	44,427
Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Misstatements in the outsourcing contract cost adjustment				0				0	0	0	0	0
Increase in pension liabilities		2,183	2,275	2,216	2,372	2,511	2,496	2,459	2,275	2,496	2,183	2,511		2,372
Increase in long term debt current							3,500			3,500
Decrease in long term debt non current							(3,500)			(3,500)
Goodwill		2,524									2,524
Additions to outsource contract costs				2,434				492	2,860	1,377	3,130	2,360		4,009	10,992
Depreciation and amortization		(2,035)	(2,412)	(1,396)	(2,373)	(1,631)	(1,624)	(1,780)	(3,808)	(3,404)	(5,844)	(5,035)		(7,408)
Increase in revenue		628	689	592					1,282		1,910				(6,433)
Cost of revenue		4,223	5,825	3,719	462	749	1,213	1,105	9,544	2,318	13,767	3,067		3,529	(1,599)
Related party expense		25	4,276	4	2,596	16	5,381	76	4,280	5,457	4,305	5,472		8,069
Decrease to selling, general and administrative expense		(2,025)	(402)	(272)	694	(16)	(345)	(76)	(674)	(421)	(2,698)	(437)		257
Increase in sundry expense (income), net		175	182	184	(784)	288	203	293	366	496	541	785
Decrease to other expense (loss)		175	182	184	(784)	288	203	293	366	496	541	784
Foreign currency translation adjustments					167									167	(25)
Increase/ (decrease) to net cash flows provided operating activities				(5,509)				(1,571)	(10,062)	(3,640)	(13,718)	(5,111)		(6,857)	28,322
Increase/ (decrease) to net cash flows provided investing activities				5,561				1,596	10,440	3,695	14,304	5,427		7,552	10,992
Increase of borrowings of other loans				6,338					12,548		19,802
Cashflows provided by financing activities				(52)				(26)	(378)	(56)	(586)	(316)		(695)	(39,314)
Decrease in third party debt modification									400			103		103	34,459
Principal repayment on other loans				6,345					12,831		20,074
Cash paid for debt issuance costs									(355)		(355)	(964)		(964)	(1,053)
Appraisal Action Liability Adjustments
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in accrued liabilities											43,100			40,600	37,800
Appraisal Action Liability Adjustments | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in accrued liabilities		43,100	42,300	41,500		39,900	39,100	38,400
Increase in interest expense		800	800	800	800	700	700	700	1,600	1,400	2,500	2,100
Outsourced Contract Cost Adjustments
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Decrease to intangible assets			15,800
Depreciation and amortization									(3,800)
Increase/ (decrease) to net cash flows provided operating activities														(11,400)	(11,000)
Increase/ (decrease) to net cash flows provided investing activities														7,600	11,000
Outsourced Contract Cost Adjustments | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Decrease to intangible assets		17,300		13,700		13,400	14,300	14,700
Additions to outsource contract costs				2,400				500	2,900	1,400	3,100	2,400
Depreciation and amortization		2,700	1,700	1,400	2,400	1,600	1,600	1,800	3,100	3,400	5,800	5,000
Increase in revenue		3,600		3,100
Cost of revenue			4,500		1,200	700	1,200	1,100	7,600		11,200	3,000
Increase/ (decrease) to net cash flows provided operating activities				(3,800)				2,300	6,700	4,800	8,900	7,400
Revenue Recognition Adjustments
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in revenue															6,400
Cost of revenue															1,600
Revenue Recognition Adjustments | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in revenue		600	700	600					1,300		1,900				$ (6,400)
Cost of revenue		600	700	600					1,300		1,900
Expense Reimbursement Adjustments
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Related party expense			4,300									5,500
Expense Reimbursement Adjustments | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in related party payables					2,600			100						8,100
Related party expense			2,100				5,400		4,300	5,500				2,400
Other Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in accrued liabilities														700
Decrease in cash and cash equivalents														10,600
Decrease in accrued compensation and benefits														2,400
Increase in pension liabilities					2,400									2,400
Other Adjustment | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase in accrued liabilities			500	400
Decrease in cash and cash equivalents		1,000	40	300		500	1,200	2,100
Increase in restricted cash		1,000	40	300		500	1,200	2,100
Decrease in accrued compensation and benefits		2,200	2,300	2,200		2,500	2,500	2,500
Increase in deferred income tax assets						800	800	800
Increase in pension liabilities		2,200	2,300	2,200		2,500	2,500	2,500	2,300	2,500	2,200	2,500
Increase in long term debt current							3,500			3,500
Decrease in long term debt non current							3,500			3,500
Goodwill		2,500									2,500
Depreciation and amortization		700	700						700
Cost of revenue			700		700				700		700
Related party expense											4,300
Decrease to selling, general and administrative expense		2,000	400	300	700		300	100	700	400	2,700	400
Increase in sundry expense (income), net		200	200	200	800	300	200	300	400	500	500	800
Decrease to other expense (loss)		$ 200	$ 200	200	$ 800	$ 300	$ 200	300	$ 400	500	500	$ 800
Lease Termination | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase/ (decrease) to net cash flows provided operating activities				50				30		60	300			200
Cashflows provided by financing activities				50				$ (30)		$ 60	300			200
Grossing Up of Borrowings and Pay Downs of Working Capital Loans [Member] | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Increase/ (decrease) to net cash flows provided operating activities														100
Increase of borrowings of other loans				6,300							19,800
Cashflows provided by financing activities														100
Decrease in third party debt modification														1,100
Increase in third party debt modification														100
Principal repayment on other loans				$ 6,300							20,100
Cash paid for debt issuance costs														$ 1,000
Cash Flow Classification Adjustment [Member] | Adjustment
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Decrease in third party debt modification											400
Cash paid for debt issuance costs											$ 400