Bank segment - Contractual Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Available-for-sale
Due in one year or less	$ 1,811
Due after one year through five years	115,714
Due after five years through ten years	14,494
Due after ten years	0
Total amortized cost	132,019
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	1,427,186
Amortized cost	1,559,205
Held-to-maturity
Due in one year or less	0
Due after one year through five years	39,824
Due after five years through ten years	20,088
Due after ten years	0
Total amortized cost	59,912
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	1,152,093
Held-to-maturity investment securities, at amortized cost	1,212,005	$ 1,251,747
Available-for-sale
Due in one year or less	1,782
Due after one year through five years	104,970
Due after five years through ten years	14,494
Due after ten years	0
Total fair value	121,246
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	1,145,166
Available-for-sale investment securities, at fair value	1,266,412	$ 1,429,667
Held-to-maturity
Due in one year or less	0
Due after one year through five years	34,133
Due after five years through ten years	16,238
Due after ten years	0
Total fair value	50,371
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	1,001,850
Held-to-maturity investment securities	$ 1,052,221