Summary of Significant Accounting Policies (Details) sqft in Thousands, $ in Thousands		12 Months Ended
	Jun. 08, 2021 USD ($)	Dec. 31, 2021 USD ($) sqft segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2016 sqft
Accounting Policies [Abstract]
Number of operating segments | segment		1
Allowance for doubtful accounts receivable		$ (200)	$ (100)
Impairment of long-lived assets		0	0
Advertising costs		1,700	1,400	$ 1,100
Accounting Policies and Supplemental Information [Line Items]
Equity method investment		8,384	0
Option to purchase		$ 11,616	0
Operating lease, number of square feet | sqft		63			19
Share-based compensation expense		$ 142,660	$ 28,211	21,757
Connexpay, LLC
Accounting Policies and Supplemental Information [Line Items]
Equity method investment		8,400
Option to purchase		$ 11,600
Restricted Stock Units with a Service and Liquidity Condition
Accounting Policies and Supplemental Information [Line Items]
Service condition satisfaction period (in years)			4 years
Award vesting period (in years)		4 years
Share-based compensation expense	$ 23,100	$ 23,100
Stock options
Accounting Policies and Supplemental Information [Line Items]
Service condition satisfaction period (in years)		4 years
Stock options | Chief Executive Officer
Accounting Policies and Supplemental Information [Line Items]
Award vesting period (in years)		7 years
Share-based compensation expense		$ 31,231	$ 10,895	6,964
Compensation and Benefits and Technology Expenses
Accounting Policies and Supplemental Information [Line Items]
Research and development costs		$ 84,100	$ 34,000	$ 25,200