Fair Value Measurement of Assets and Liabilities - Recurring and Non-Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Investment securities:
Equity securities	$ 78,296	$ 71,513
Available for sale debt securities:
Available for sale debt securities	4,117,121	3,369,724
Loans held for sale	5,405	16,931
Non-recurring fair value measurements:
Unpaid principal balances of loans held for sale	5,300	16,800
U.S. Treasury securities
Available for sale debt securities:
Available for sale debt securities	326,744	291,549
U.S. government agency securities
Available for sale debt securities:
Available for sale debt securities	39,769	22,543
Obligations of states and political subdivisions
Available for sale debt securities:
Available for sale debt securities	191,009	192,509
Residential mortgage-backed securities
Available for sale debt securities:
Available for sale debt securities	3,326,099	2,681,076
Corporate and other debt securities
Available for sale debt securities:
Available for sale debt securities	233,500	182,047
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements
Investment securities:
Equity securities	23,435	23,642
Available for sale debt securities:
Available for sale debt securities	326,744	291,549
Loans held for sale	0	0
Other assets	0	0
Total assets	350,179	315,191
Liabilities
Other liabilities	0	0
Total liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements | U.S. Treasury securities
Available for sale debt securities:
Available for sale debt securities	326,744	291,549
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements | U.S. government agency securities
Available for sale debt securities:
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements | Obligations of states and political subdivisions
Available for sale debt securities:
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements | Residential mortgage-backed securities
Available for sale debt securities:
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring fair value measurements | Corporate and other debt securities
Available for sale debt securities:
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-recurring fair value measurements
Non-recurring fair value measurements:
Non-performing loan held for sale		0
Collateral dependent loans	0	0
Foreclosed assets	0	0
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-recurring fair value measurements | Non-performing loan held for sale
Available for sale debt securities:
Loans held for sale	0
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements
Investment securities:
Equity securities	0	0
Available for sale debt securities:
Available for sale debt securities	3,790,377	3,078,175
Loans held for sale	5,405	16,931
Other assets	187,786	444,263
Total assets	3,983,568	3,539,369
Liabilities
Other liabilities	194,604	454,200
Total liabilities	194,604	454,200
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements | U.S. Treasury securities
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements | U.S. government agency securities
Available for sale debt securities:
Available for sale debt securities	39,769	22,543
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements | Obligations of states and political subdivisions
Available for sale debt securities:
Available for sale debt securities	191,009	192,509
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements | Residential mortgage-backed securities
Available for sale debt securities:
Available for sale debt securities	3,326,099	2,681,076
Significant Other Observable Inputs (Level 2) | Recurring fair value measurements | Corporate and other debt securities
Available for sale debt securities:
Available for sale debt securities	233,500	182,047
Significant Other Observable Inputs (Level 2) | Non-recurring fair value measurements
Non-recurring fair value measurements:
Non-performing loan held for sale		8,750
Collateral dependent loans	0	0
Foreclosed assets	0	0
Total	12,687	8,750
Significant Other Observable Inputs (Level 2) | Non-recurring fair value measurements | Non-performing loan held for sale
Available for sale debt securities:
Loans held for sale	12,687
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements
Investment securities:
Equity securities	0	0
Available for sale debt securities:
Available for sale debt securities	0	0
Loans held for sale	0	0
Other assets	0	0
Total assets	0	0
Liabilities
Other liabilities	0	0
Total liabilities	0	0
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements | U.S. Treasury securities
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements | U.S. government agency securities
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements | Obligations of states and political subdivisions
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements | Residential mortgage-backed securities
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) | Recurring fair value measurements | Corporate and other debt securities
Available for sale debt securities:
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) | Non-recurring fair value measurements
Non-recurring fair value measurements:
Non-performing loan held for sale		0
Collateral dependent loans	136,544	139,424
Foreclosed assets	5,664	13,852
Total	142,208	153,276
Significant Unobservable Inputs (Level 3) | Non-recurring fair value measurements | Non-performing loan held for sale
Available for sale debt securities:
Loans held for sale	0
Fair Value | Recurring fair value measurements
Available for sale debt securities:
Available for sale debt securities	4,117,121	3,369,724
Loans held for sale	5,405	16,931
Other assets	187,786	444,263
Total assets	4,344,019	3,865,560
Liabilities
Other liabilities	194,604	454,200
Total liabilities	194,604	454,200
Fair Value | Recurring fair value measurements | U.S. Treasury securities
Available for sale debt securities:
Available for sale debt securities	326,744	291,549
Fair Value | Recurring fair value measurements | U.S. government agency securities
Available for sale debt securities:
Available for sale debt securities	39,769	22,543
Fair Value | Recurring fair value measurements | Obligations of states and political subdivisions
Available for sale debt securities:
Available for sale debt securities	191,009	192,509
Fair Value | Recurring fair value measurements | Residential mortgage-backed securities
Available for sale debt securities:
Available for sale debt securities	3,326,099	2,681,076
Fair Value | Recurring fair value measurements | Corporate and other debt securities
Available for sale debt securities:
Available for sale debt securities	233,500	182,047
Fair Value | Non-recurring fair value measurements
Non-recurring fair value measurements:
Non-performing loan held for sale		8,750
Collateral dependent loans	136,544	139,424
Foreclosed assets	5,664	13,852
Total	154,895	162,026
Fair Value | Non-recurring fair value measurements | Non-performing loan held for sale
Available for sale debt securities:
Loans held for sale	12,687
Fair Value | Fair Value, Inputs, Level 1, Level 2, and Level 3 | Recurring fair value measurements
Investment securities:
Equity securities	23,435	23,642
Fair Value | Significant Unobservable Inputs (Level 3)
Investment securities:
Equity securities	44,589	36,871
Fair Value | NAV | Recurring fair value measurements
Investment securities:
Equity securities	$ 10,272	$ 11,000