Fair Value of Financial Instruments - Fair Value Estimates (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Assets
HTM investment securities	$ 1,427,324	$ 1,485,506
AFS investment securities	1,320,050	1,140,071
Derivative assets	41,532	44,939
Accrued interest receivable	69,629	68,516
Liabilities
Derivative liabilities	11,968	13,603
Level 1
Assets
Cash and cash equivalents	899,817	936,473
HTM investment securities	0	0
AFS investment securities	0	0
Equity securities	589	759
Loans held for sale	0
Loans held for investment, net	0	0
Derivative assets	4	1
Accrued interest receivable	0	0
Liabilities
Deposit accounts	0	0
FHLB advances	0	0
Subordinated debentures	0	0
Derivative liabilities	0	10
Accrued interest payable	0	0
Level 1 | Interest-bearing time deposits with financial institutions
Assets
Cash and cash equivalents	996	995
Level 2
Assets
Cash and cash equivalents	0	0
HTM investment securities	1,427,324	1,485,506
AFS investment securities	1,320,050	1,140,071
Equity securities	0	0
Loans held for sale	146
Loans held for investment, net	0	0
Derivative assets	6,422	5,643
Accrued interest receivable	69,629	68,516
Liabilities
Deposit accounts	14,643,853	15,003,769
FHLB advances	199,323	592,480
Subordinated debentures	324,577	320,687
Derivative liabilities	11,987	10,705
Accrued interest payable	17,356	18,671
Level 2 | Interest-bearing time deposits with financial institutions
Assets
Cash and cash equivalents	0	0
Level 3
Assets
Cash and cash equivalents	0	0
HTM investment securities	0	0
AFS investment securities	0	0
Equity securities	0	0
Loans held for sale	0
Loans held for investment, net	11,796,323	12,562,323
Derivative assets	0	0
Accrued interest receivable	0	0
Liabilities
Deposit accounts	0	0
FHLB advances	0	0
Subordinated debentures	0	0
Derivative liabilities	0	0
Accrued interest payable	0	0
Level 3 | Interest-bearing time deposits with financial institutions
Assets
Cash and cash equivalents	0	0
Carrying Amount
Assets
Cash and cash equivalents	899,817	936,473
HTM investment securities	1,710,141	1,729,541
AFS investment securities	1,320,050	1,140,071
Equity securities	589	759
Loans held for sale	140
Loans held for investment, net	12,489,951	13,289,020
Derivative assets	6,426	5,644
Accrued interest receivable	69,629	68,516
Liabilities
Deposit accounts	14,627,654	14,995,626
FHLB advances	200,000	600,000
Subordinated debentures	332,160	331,842
Derivative liabilities	11,987	10,715
Accrued interest payable	17,356	18,671
Carrying Amount | Interest-bearing time deposits with financial institutions
Assets
Cash and cash equivalents	996	995
Estimated Fair Value
Assets
Cash and cash equivalents	899,817	936,473
HTM investment securities	1,427,324	1,485,506
AFS investment securities	1,320,050	1,140,071
Equity securities	589	759
Loans held for sale	146
Loans held for investment, net	11,796,323	12,562,323
Derivative assets	6,426	5,644
Accrued interest receivable	69,629	68,516
Liabilities
Deposit accounts	14,643,853	15,003,769
FHLB advances	199,323	592,480
Subordinated debentures	324,577	320,687
Derivative liabilities	11,987	10,715
Accrued interest payable	17,356	18,671
Estimated Fair Value | Interest-bearing time deposits with financial institutions
Assets
Cash and cash equivalents	$ 996	$ 995