Investment Securities - Unrealized Gross Losses and Fair Values of Securities in a Continuous Loss Position (Details)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2025 USD ($) security	Jun. 30, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Securities in the available-for-sale portfolio in a continuous loss position
Number of individual securities in a continuous loss position | security	144	144	159
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses	$ (242,000)	$ (242,000)	$ (4,775,000)
12 Months or More Unrealized Losses	(207,932,000)	(207,932,000)	(259,563,000)
Total Unrealized Losses	(208,174,000)	(208,174,000)	(264,338,000)
Time in Continuous Loss, Fair Value
Less Than 12 Months Fair Value	129,584,000	129,584,000	277,688,000
12 Months or More Fair Value	1,384,860,000	1,384,860,000	1,443,285,000
Total Fair Value	1,514,444,000	$ 1,514,444,000	$ 1,720,973,000
Number of securities with intent to sell		0	0
Credit losses recognized on securities	0	$ 0	$ 0
Allowance for credit losses, investment securities	0	$ 0	$ 0
Investment securities comprised of collateralized loan obligations rated AA or better, obligations issued by local state and political subdivisions rated AA or better and non-agency commercial mortgage-backed securities rated AAA		5.00%	5.00%
Government agency debt securities
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses			$ (23,000)
Total Unrealized Losses			(23,000)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value			8,147,000
Total Fair Value			8,147,000
Residential - Government agency
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses			(154,000)
12 Months or More Unrealized Losses	(1,209,000)	$ (1,209,000)	(1,460,000)
Total Unrealized Losses	(1,209,000)	(1,209,000)	(1,614,000)
Time in Continuous Loss, Fair Value
Less Than 12 Months Fair Value			27,127,000
12 Months or More Fair Value	8,540,000	8,540,000	8,732,000
Total Fair Value	8,540,000	8,540,000	35,859,000
Residential - Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses	(119,000)	(119,000)	(2,997,000)
12 Months or More Unrealized Losses	(72,534,000)	(72,534,000)	(99,726,000)
Total Unrealized Losses	(72,653,000)	(72,653,000)	(102,723,000)
Time in Continuous Loss, Fair Value
Less Than 12 Months Fair Value	82,667,000	82,667,000	116,084,000
12 Months or More Fair Value	594,518,000	594,518,000	622,029,000
Total Fair Value	677,185,000	677,185,000	738,113,000
Commercial - Government agency
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(49,424,000)	(49,424,000)	(53,223,000)
Total Unrealized Losses	(49,424,000)	(49,424,000)	(53,223,000)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	194,010,000	194,010,000	196,125,000
Total Fair Value	194,010,000	194,010,000	196,125,000
Commercial - Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(1,931,000)	(1,931,000)	(3,107,000)
Total Unrealized Losses	(1,931,000)	(1,931,000)	(3,107,000)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	43,913,000	43,913,000	44,908,000
Total Fair Value	43,913,000	43,913,000	44,908,000
Government agency
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses	(123,000)	(123,000)	(712,000)
12 Months or More Unrealized Losses	(42,650,000)	(42,650,000)	(54,202,000)
Total Unrealized Losses	(42,773,000)	(42,773,000)	(54,914,000)
Time in Continuous Loss, Fair Value
Less Than 12 Months Fair Value	46,917,000	46,917,000	76,968,000
12 Months or More Fair Value	300,687,000	300,687,000	310,171,000
Total Fair Value	347,604,000	347,604,000	387,139,000
Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses			(912,000)
12 Months or More Unrealized Losses	(40,184,000)	(40,184,000)	(47,822,000)
Total Unrealized Losses	(40,184,000)	(40,184,000)	(48,734,000)
Time in Continuous Loss, Fair Value
Less Than 12 Months Fair Value			57,509,000
12 Months or More Fair Value	243,192,000	243,192,000	253,173,000
Total Fair Value	$ 243,192,000	$ 243,192,000	$ 310,682,000