Restatement of Previously Issued Financial Statements - Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 20,775	$ 68,221
Restricted cash		27,285	2,088
Accounts receivable, net of allowance for doubtful accounts of $6,049		184,102	206,868
Related party receivables and prepaid expenses		715	711
Inventories, net		15,215	14,314
Prepaid expenses and other current assets		31,799	31,091
Total current assets		279,891	323,293
Property, plant and equipment, net of accumulated depreciation of $196,683 and $193,760, respectively		73,449	87,851
Operating lease right-of-use assets, net		53,937	68,861
Goodwill		358,323	359,781	$ 359,771
Intangible assets, net		244,539	292,664
Deferred income tax assets		2,109	6,606
Other noncurrent assets		24,775	18,723
Total assets		1,037,023	1,157,779
Current liabilities
Accounts payable		61,744	76,027
Related party payables		1,484
Income tax payable		3,551	2,466
Accrued liabilities		113,519	126,399
Accrued compensation and benefits		60,860	63,467
Accrued interest		10,075	48,769
Customer deposits		17,707	21,277
Deferred revenue		16,617	16,377
Obligation for claim payment		46,902	29,328
Current portion of operating lease liabilities		15,923	18,349
Current portion of finance lease liabilities		6,683	12,231
Current portion of long-term debts		236,775	39,952
Total current liabilities		591,840	454,739
Long-term debt, net of current maturities		1,012,452	1,498,004
Finance lease liabilities, net of current portion		9,156	13,287
Pension liabilities, net		28,383	35,515
Deferred income tax liabilities		11,594	9,569
Long-term income tax liabilities		3,201	2,759
Operating lease liabilities, net of current portion		41,170	56,814
Other long-term liabilities		5,999	13,624
Total liabilities		1,703,795	2,084,311
Commitments and Contingencies (Note 14)
Stockholders' equity (deficit)
Common stock, par value of $0.0001 per share; 1,600,000,000 shares authorized; 267,646,667 shares issued and 265,194,961 shares outstanding at December 31, 2021		37	15
Preferred stock, par value of $0.0001 per share; 20,000,000 shares authorized; 2,778,111 shares issued and outstanding at December 31, 2021		1	1
Additional paid in capital		838,853	446,739
Less: Common stock held in treasury, at cost; 2,451,706 shares at December 31, 2021		(10,949)	(10,949)
Equity-based compensation		56,123	52,183
Accumulated deficit		(1,532,428)	(1,390,038)
Accumulated other comprehensive loss:
Foreign currency translation adjustment		(7,463)	(7,419)
Unrealized pension actuarial losses, net of tax		(10,946)	(17,064)
Total accumulated other comprehensive loss		(18,409)	(24,483)
Total stockholders' deficit		(666,772)	(926,532)	$ (743,040)	$ (241,259)
Total liabilities and stockholders' deficit		1,037,023	$ 1,157,779
As previously reported
Current assets
Cash and cash equivalents		20,775
Restricted cash		27,285
Accounts receivable, net of allowance for doubtful accounts of $6,049		184,102
Related party receivables and prepaid expenses		715
Inventories, net		15,215
Prepaid expenses and other current assets		31,799
Total current assets		279,891
Property, plant and equipment, net of accumulated depreciation of $196,683 and $193,760, respectively		73,449
Operating lease right-of-use assets, net		53,937
Goodwill		358,323
Intangible assets, net		244,539
Deferred income tax assets		2,109
Other noncurrent assets		24,775
Total assets		1,037,023
Current liabilities
Accounts payable		61,744
Related party payables		1,484
Income tax payable		3,551
Accrued liabilities		113,519
Accrued compensation and benefits		60,860
Accrued interest		10,075
Customer deposits		17,707
Deferred revenue		16,617
Obligation for claim payment		46,902
Current portion of operating lease liabilities		15,923
Current portion of finance lease liabilities		6,683
Current portion of long-term debts	$ 138,700	144,828
Total current liabilities		499,893
Long-term debt, net of current maturities		1,104,399
Finance lease liabilities, net of current portion		9,156
Pension liabilities, net		28,383
Deferred income tax liabilities		11,594
Long-term income tax liabilities		3,201
Operating lease liabilities, net of current portion		41,170
Other long-term liabilities		5,999
Total liabilities		1,703,795
Stockholders' equity (deficit)
Common stock, par value of $0.0001 per share; 1,600,000,000 shares authorized; 267,646,667 shares issued and 265,194,961 shares outstanding at December 31, 2021		37
Preferred stock, par value of $0.0001 per share; 20,000,000 shares authorized; 2,778,111 shares issued and outstanding at December 31, 2021		1
Additional paid in capital		838,853
Less: Common stock held in treasury, at cost; 2,451,706 shares at December 31, 2021		(10,949)
Equity-based compensation		56,123
Accumulated deficit		(1,532,428)
Accumulated other comprehensive loss:
Foreign currency translation adjustment		(7,463)
Unrealized pension actuarial losses, net of tax		(10,946)
Total accumulated other comprehensive loss		(18,409)
Total stockholders' deficit		(666,772)
Total liabilities and stockholders' deficit		1,037,023
Adjustment
Current liabilities
Current portion of long-term debts		91,947
Total current liabilities		91,947
Long-term debt, net of current maturities		$ (91,947)