REVENUE - Summary of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 67,285	$ 62,075	$ 200,538	$ 172,068
Deferred implementation costs, net	0	1,442	0	1,442	$ 0	$ 0	$ 2,173	$ 3,785
Commodity Contract Asset, Current	53		53			78
Deferred revenue	3,004		3,004			3,280
Deferred revenue	1,363		1,363			1,800
Bridg Acquisition
Disaggregation of Revenue [Line Items]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	44		44			52
Deferred implementation costs, net	9		9			26
Deferred revenue	1,305		1,305			1,627
Contract with Customer, Liability, Noncurrent	58		58			$ 173
Cost per Served Sale
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	43,436	41,494	128,568	116,969
Cost per Redemption
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	21,602	20,220	65,333	53,980
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,247	361	6,637	1,119
Subscription revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5,421	2,845	15,471	4,844
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	64	30	155
Bridg platform revenue(1)
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 5,421	$ 2,909	$ 15,501	$ 4,999