Bank segment - Loans Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 6,058,091		$ 6,210,578
Less: Deferred fees and discounts	(27,933)		(29,768)
Allowance for credit losses	(66,813)	$ (71,057)	(74,372)	$ (69,068)	$ (71,296)	$ (72,216)
Loans held for investment, net	5,963,345		6,106,438
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	5,165,168		5,195,019
Residential 1-4 family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,603,825		2,595,162
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,368,907		1,374,038
Home equity line of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	973,216		1,017,207
Residential land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	20,818		18,364
Commercial construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	181,148		172,405
Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	17,254		17,843
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	648,286		743,303
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 244,637		$ 272,256