Equity method investment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Technology, trade name and customer relationship intangibles	$ 29,216		$ 29,216		$ 34,555
Amortization of Intangible Assets	1,765	$ 1,951	5,339	$ 5,873
Dividends received from equity method investment			33,159	59,401
Loans	31,943,284		31,943,284		29,041,605
Bankers Healthcare Group, LLC
Schedule of Equity Method Investments [Line Items]
Technology, trade name and customer relationship intangibles	6,100		6,100		6,300
Amortization of Intangible Assets	88	128	262	384
Accretion income	43	164	183	595
Dividends received from equity method investment	5,600	18,600	33,200	59,400
Payments to Acquire Loans Held-for-investment	0	$ 49,600	0	$ 125,600
Loans	$ 283,600		$ 283,600		$ 350,600