Segment Reporting - Financial Information by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 550,590	$ 393,593	$ 448,737
Operating expenses	162,555	114,892	124,821
Selling, general and administrative expenses	110,438	77,912	76,300
Other income, net	(12,895)	(11,885)	(11,092)
Segment profit (loss)	111,866	37,816	96,455
Depreciation and amortization	116,753	116,570	115,566
Loss on disposal of assets, net	48	274	205
Impairment of property and equipment			5,898
Change in fair value of private placement warrants	7,600	1,133	16,267
Tax receivable agreement liability adjustment	(1,016)	6,850	(106)
Stock-based compensation	13,784	12,589	10,012
Loss on extinguishment of debt	5,334
Interest expense, net	44,942	40,865	60,729
Income (loss) before income taxes	67,901	853	30,657
Service Revenue
Segment Reporting Information [Line Items]
Total revenue	492,846	336,274	416,723
Cost of revenue	5,337	3,967	5,561
Product Sales
Segment Reporting Information [Line Items]
Total revenue	57,744	57,319	32,014
Cost of revenue	29,809	29,573	13,919
Operating Segments
Segment Reporting Information [Line Items]
Segment profit (loss)	255,346	179,134	239,228
Operating Segments | Government Solutions
Segment Reporting Information [Line Items]
Total revenue	283,155	212,737	172,258
Operating expenses	96,284	62,387	57,905
Selling, general and administrative expenses	52,380	34,465	32,696
Other income, net	(2,040)	(111)	(278)
Segment profit (loss)	106,650	85,018	66,164
Loss on disposal of assets, net	48	258	60
Impairment of property and equipment			5,898
Income (loss) before income taxes	106,602	84,760	60,206
Operating Segments | Commercial Services
Segment Reporting Information [Line Items]
Total revenue	260,899	180,856	276,479
Operating expenses	65,718	52,505	66,916
Selling, general and administrative expenses	42,873	40,978	41,384
Other income, net	(10,837)	(11,774)	(10,814)
Segment profit (loss)	159,962	96,585	175,284
Loss on disposal of assets, net		16	145
Income (loss) before income taxes	159,962	96,569	175,139
Operating Segments | Parking Solutions
Segment Reporting Information [Line Items]
Total revenue	6,536
Operating expenses	553
Selling, general and administrative expenses	1,488
Other income, net	(18)
Segment profit (loss)	2,431
Income (loss) before income taxes	2,431
Operating Segments | Service Revenue | Government Solutions
Segment Reporting Information [Line Items]
Total revenue	227,992	155,418	140,244
Cost of revenue	1,500	1,405	1,852
Operating Segments | Service Revenue | Commercial Services
Segment Reporting Information [Line Items]
Total revenue	260,899	180,856	276,479
Cost of revenue	3,183	2,562	3,709
Operating Segments | Service Revenue | Parking Solutions
Segment Reporting Information [Line Items]
Total revenue	3,955
Cost of revenue	654
Operating Segments | Product Sales | Government Solutions
Segment Reporting Information [Line Items]
Total revenue	55,163	57,319	32,014
Cost of revenue	28,381	29,573	13,919
Operating Segments | Product Sales | Parking Solutions
Segment Reporting Information [Line Items]
Total revenue	2,581
Cost of revenue	1,428
Corporate and Other
Segment Reporting Information [Line Items]
Selling, general and administrative expenses	13,697	2,469	2,220
Segment profit (loss)	(13,697)	(2,469)	(2,220)
Depreciation and amortization	116,753	116,570	115,566
Change in fair value of private placement warrants	7,600	1,133	16,267
Tax receivable agreement liability adjustment	(1,016)	6,850	(106)
Stock-based compensation	13,784	12,589	10,012
Loss on extinguishment of debt	5,334
Interest expense, net	44,942	40,865	60,729
Income (loss) before income taxes	$ (201,094)	$ (180,476)	$ (204,688)