Other Significant Transactions - Additional Information (Details) $ / shares in Units, $ in Thousands				3 Months Ended		6 Months Ended		9 Months Ended
		Jan. 27, 2020 USD ($) $ / shares	Apr. 26, 2019 $ / shares	Jun. 30, 2022 USD ($) yr $ / shares	Jun. 30, 2021 USD ($) yr	Jun. 30, 2022 USD ($) yr $ / shares shares	Jun. 30, 2021 USD ($) yr	Sep. 30, 2021 shares	Dec. 31, 2021 USD ($)	Oct. 17, 2018 USD ($)
Related Party Transaction [Line Items]
Revenue				$ 187,487	$ 128,657	$ 357,872	$ 218,515
Term of volatility and risk free rates utilizing a peer group | yr					5		5
Redflex Irish Investments Pty Ltd
Related Party Transaction [Line Items]
Revenue				200		500
Cost method investment				3,500		$ 3,500			$ 3,700
Percentage of Non-Voting Interest Acquired						16.00%
Minimum | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Common stock price threshold trading days			10 days
Minimum | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Common stock price threshold trading days		10 days
Maximum | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Common stock price threshold trading days			20 days
Maximum | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Common stock price threshold trading days		20 days
Verra Mobility Business Combination
Related Party Transaction [Line Items]
Payable to related party pursuant to tax receivable agreement, current portion				5,100		$ 5,100
Tax Receivable Agreement, portion of net cash savings paid out						50.00%
Tax Receivable Agreement, portion of net cash savings retained						50.00%
Estimated maximum benefit to be paid to tax receivable agreement				70,000		$ 70,000
Increase to payable related to tax receivable agreement adjustment				1,000	$ 1,700	1,000	$ 1,700
Tax receivable agreement, amount payable				60,800		60,800
Tax receivable agreement, amount payable, non-current				55,700		$ 55,700
Contingency period						5 years
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $13.00 and $15.50
Related Party Transaction [Line Items]
Earn-out shares issuable if condition met | shares								5,000,000
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $13.00 and $15.50 | Common Stock Including Additional Paid in Capital
Related Party Transaction [Line Items]
Earn-out shares issued value		$ 36,600
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Common stock price | $ / shares			$ 13.00
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $13.00 | Potential Future Shares
Related Party Transaction [Line Items]
Earn-out shares issued value				0		$ 0
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Common stock price | $ / shares		$ 15.50
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $15.50 | Common Stock Contingent Consideration
Related Party Transaction [Line Items]
Earn-out shares issued value		$ 36,600
Verra Mobility Business Combination | Platinum Stockholder | Common Stock Price Greater than $15.50 | Potential Future Shares
Related Party Transaction [Line Items]
Earn-out shares issued value				5,000		5,000
Verra Mobility Business Combination | Platinum Stockholder | Earn-Out Agreement
Related Party Transaction [Line Items]
Contingent consideration				$ 36,600		$ 36,600				$ 73,150
Term of volatility and risk free rates utilizing a peer group | yr				5		5
Verra Mobility Business Combination | Platinum Stockholder | Earn-Out Agreement | Earn-Out Scenario Five
Related Party Transaction [Line Items]
Earn-out shares issuable if condition met | shares						0
Verra Mobility Business Combination | Platinum Stockholder | Earn-Out Agreement | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Earn-out shares issuable if condition met | shares						2,500,000
Common stock price | $ / shares	[1]			$ 13.00		$ 13.00
Verra Mobility Business Combination | Platinum Stockholder | Earn-Out Agreement | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Earn-out shares issuable if condition met | shares						2,500,000
Common stock price | $ / shares	[1]			$ 15.50		$ 15.50
Verra Mobility Business Combination | Minimum
Related Party Transaction [Line Items]
Common stock price threshold trading days						10 days
Verra Mobility Business Combination | Minimum | Platinum Stockholder | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Common stock price threshold trading days			10 days
Verra Mobility Business Combination | Minimum | Platinum Stockholder | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Common stock price threshold trading days		10 days
Verra Mobility Business Combination | Maximum
Related Party Transaction [Line Items]
Common stock price threshold trading days						20 days
Verra Mobility Business Combination | Maximum | Platinum Stockholder | Common Stock Price Greater than $13.00
Related Party Transaction [Line Items]
Common stock price threshold trading days			20 days
Verra Mobility Business Combination | Maximum | Platinum Stockholder | Common Stock Price Greater than $15.50
Related Party Transaction [Line Items]
Common stock price threshold trading days		20 days
Verra Mobility Business Combination | Maximum | Platinum Stockholder | Earn-Out Agreement
Related Party Transaction [Line Items]
Earn-out shares issuable if condition met | shares						10,000,000

[1] The first and second tranches of Earn-Out Shares have been issued, as discussed below.