Acquired Card Receivables - Summary of Change in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021
Acquired Card Receivables [Abstract]
Balance, beginning	$ 1,740
Initial allowance for credit losses on purchased card receivables with credit deterioration	14	$ 2,082
Provision for expected credit losses	4,035	462
Charge-off amounts	(2,276)	(828)
Recoveries collected	204	24
Balance, end of period	$ 3,717	$ 1,740