ACQUISITION - Pro Forma Nonrecurring Adjustments (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												6 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Weighted average number of common shares outstanding
Basic (in shares)	60,065,978	60,065,053	60,059,936	60,053,912	54,064,750	53,637,085	52,150,106	47,573,364	40,331,993	40,327,697	40,308,934	38,488,005	49,861,735	39,398,469	51,101,813	39,703,690	60,061,243	51,840,518	39,860,335
Diluted (in shares)	60,065,978	60,065,053	60,059,936	60,053,912	54,064,750	53,637,085	52,150,106	47,573,364	40,331,993	40,327,697	40,308,934	38,488,005	49,861,735	39,398,469	51,101,813	39,703,690	60,061,243	51,840,518	39,860,335
Cantaloupe
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenue																		$ 140,575	$ 121,373
Net loss attributable to USAT																		(7,256)	(13,828)
Net loss attributable to USAT common shares																		$ (7,924)	$ (14,496)
Net loss per share
Basic (in dollars per share)																		$ (0.15)	$ (0.27)
Diluted (in dollars per share)																		$ (0.15)	$ (0.27)
Weighted average number of common shares outstanding
Basic (in shares)																		53,717,133	52,849,217
Diluted (in shares)																		53,717,133	52,849,217