Other Borrowings and Subordinated Notes and Debentures - Debt Components (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2018
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 1,238,053	$ 1,238,053	$ 1,338,507
FHLB advances, net of discount, due 2024 to 2033, 4.56% to 5.60% secured by real estate loans
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 853,154	$ 853,154	953,222
FHLB advances, net of discount, due 2024 to 2033, 4.56% to 5.60% secured by real estate loans | Minimum
Debt Instrument [Line Items]
Fixed rate (as percent)	4.56%	4.56%
FHLB advances, net of discount, due 2024 to 2033, 4.56% to 5.60% secured by real estate loans | Maximum
Debt Instrument [Line Items]
Fixed rate (as percent)	5.60%	5.60%
Other long-term debt
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 18,720	$ 18,720	19,144
Total other borrowings
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 871,874	$ 871,874	972,366
Subordinated Notes
Debt Instrument [Line Items]
Fixed rate (as percent)				5.00%
Subordinated Notes | LIBOR
Debt Instrument [Line Items]
Floating rate (as percent)		2.15%
Subordinated Notes | SOFR
Debt Instrument [Line Items]
Floating rate (as percent)	0.26161%	0.26161%
Subordinated Notes | Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly)
Debt Instrument [Line Items]
Long-term debt, gross	$ 330,000	$ 330,000	330,000
Fixed rate (as percent)	5.00%	5.00%
Subordinated Notes | Subordinated notes payable, due 4/1/2028, fixed-to-floating rate (fixed rate of 5.00% through 3/31/2023, floating rate of 2.15% above the three month LIBOR rate, reset quarterly) | LIBOR
Debt Instrument [Line Items]
Floating rate (as percent)	2.15%
Subordinated Notes | Subordinated notes payable, net of premium adjustments, due 7/31/2030, fixed-to-floating rate (fixed rate of 6.00% through 7/30/2025, floating rate of 5.92% above the three month SOFR rate, reset quarterly)
Debt Instrument [Line Items]
Long-term debt, gross	$ 37,142	$ 37,142	37,171
Fixed rate (as percent)	6.00%	6.00%
Subordinated Notes | Subordinated notes payable, net of premium adjustments, due 7/31/2030, fixed-to-floating rate (fixed rate of 6.00% through 7/30/2025, floating rate of 5.92% above the three month SOFR rate, reset quarterly) | SOFR
Debt Instrument [Line Items]
Floating rate (as percent)	5.92%
Total subordinated notes and debentures
Debt Instrument [Line Items]
Total other borrowings and subordinated debt	$ 366,179	$ 366,179	366,141
Unamortized debt issuance costs	$ (963)	$ (963)	$ (1,030)