Segment and Geographic Area Information - Revenue by segment information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Segment information
Number of segments | segment									3
Revenue	$ 294,312	$ 279,229	$ 293,009	$ 300,056	$ 314,109	$ 305,280	$ 307,722	$ 365,451	$ 1,166,606	$ 1,292,562	$ 1,562,337
Cost of revenue (exclusive of depreciation and amortization)	235,697	211,731	209,080	232,587	254,995	234,222	241,788	292,539	889,095	1,023,544	1,224,735
Segment profit									277,511	269,018	337,602
Selling, general and administrative expenses (exclusive of depreciation and amortization)	48,262	43,244	36,390	41,885	45,879	42,837	47,014	50,374	169,781	186,104	198,864
Depreciation and amortization	19,037	19,094	19,420	19,599	25,826	22,095	22,847	23,185	77,150	93,953	100,903
Related party expense									9,191	5,381	9,501
Interest expense, net	40,293	41,757	42,867	43,131	44,238	43,612	44,440	41,588	168,048	173,878	163,449
Sundry expense (income), net	801	136	(787)	213	98	(434)	(899)	1,082	363	(153)	969
Other expense (income), net	(768)	366	651	152	10,867	(10,414)	(584)	(34,657)	401	(34,788)	14,429
Net loss before income taxes	(62,383)	(11,773)	(17,360)	(39,218)	(78,707)	(27,998)	(48,030)	(10,211)	(130,734)	(164,946)	(501,474)
I T P S Segment [Member]
Segment information
Revenue	216,687	208,304	217,260	231,875	243,537	234,365	243,029	284,112	874,126	1,005,043	1,234,284
Cost of revenue (exclusive of depreciation and amortization)	172,299	157,721	156,669	185,502	200,387	183,671	195,835	235,120	672,191	815,013	1,001,655
Segment profit									201,935	190,030	232,629
H S Segment [Member]
Segment information
Revenue	56,547	53,995	56,204	51,093	51,623	54,209	49,166	64,049	217,839	219,047	256,721
Cost of revenue (exclusive of depreciation and amortization)	46,709	41,945	38,973	35,818	39,394	39,444	36,148	44,931	163,445	159,917	180,045
Segment profit									54,394	59,130	76,676
L L P S Segment [Member]
Segment information
Revenue	21,078	16,930	19,545	17,088	18,949	16,706	15,527	17,290	74,641	68,472	71,332
Cost of revenue (exclusive of depreciation and amortization)	$ 16,689	$ 12,065	$ 13,438	$ 11,267	$ 15,214	$ 11,107	$ 9,805	$ 12,488	53,459	48,614	43,035
Segment profit									$ 21,182	$ 19,858	$ 28,297