Investment Securities - Unrealized Gross Losses and Fair Values of Securities in a Continuous Loss Position (Details) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2023 USD ($) security shares	Jun. 30, 2024 USD ($) security shares	Dec. 31, 2023 USD ($) security shares	Dec. 31, 2016 shares
Securities in the available-for-sale portfolio in a continuous loss position
Number of individual securities in a continuous loss position | security	222	189	222
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses	$ (564)		$ (564)
12 Months or More Unrealized Losses	(302,818)	$ (311,676)	(302,818)
Total Unrealized Losses	(303,382)	(311,676)	(303,382)
Time in Continuous Loss, Fair Value
Less Than 12 Months, Fair Value	63,667	22,000	63,667
12 Months or More Fair Value	2,170,608	1,827,928	2,170,608
Total Fair Value	2,234,275	1,849,928	2,234,275
Allowance for credit losses, investment securities	0	$ 0	$ 0
Investment securities comprised of collateralized loan obligations rated AA or better and obligations issued by local state and political subdivisions rated AA or better		5.00%
Class B restricted shares
Time in Continuous Loss, Fair Value
Net realized gain	$ 40,800
Shares held | shares	0	0	0
Number of shares sold | shares			120,000
Class B restricted shares | Visa
Time in Continuous Loss, Fair Value
Number of shares sold | shares				274,000
U.S. Treasury and government agency debt securities
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	$ (666)	$ (318)	$ (666)
Total Unrealized Losses	(666)	(318)	(666)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	32,503	12,969	32,503
Total Fair Value	32,503	12,969	32,503
Government-sponsored enterprises debt securities
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(408)	(332)	(408)
Total Unrealized Losses	(408)	(332)	(408)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	19,592	19,668	19,592
Total Fair Value	19,592	19,668	19,592
Residential - Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(112,124)	(117,207)	(112,124)
Total Unrealized Losses	(112,124)	(117,207)	(112,124)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	783,297	721,145	783,297
Total Fair Value	783,297	721,145	783,297
Residential - Government agency
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(1,121)	(1,430)	(1,121)
Total Unrealized Losses	(1,121)	(1,430)	(1,121)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	10,182	9,335	10,182
Total Fair Value	10,182	9,335	10,182
Commercial - Government agency
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(50,270)	(54,620)	(50,270)
Total Unrealized Losses	(50,270)	(54,620)	(50,270)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	218,674	208,228	218,674
Total Fair Value	218,674	208,228	218,674
Commercial - Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(7,028)	(6,535)	(7,028)
Total Unrealized Losses	(7,028)	(6,535)	(7,028)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	86,431	82,492	86,431
Total Fair Value	86,431	82,492	86,431
Commercial - Non-agency
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(281)		(281)
Total Unrealized Losses	(281)		(281)
Time in Continuous Loss, Fair Value
Less Than 12 Months, Fair Value		22,000
12 Months or More Fair Value	21,683		21,683
Total Fair Value	21,683	22,000	21,683
Government agency
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(67,568)	(70,324)	(67,568)
Total Unrealized Losses	(67,568)	(70,324)	(67,568)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	471,150	434,856	471,150
Total Fair Value	471,150	434,856	471,150
Government-sponsored enterprises
Time in Continuous Loss, Unrealized Losses
12 Months or More Unrealized Losses	(61,856)	(60,910)	(61,856)
Total Unrealized Losses	(61,856)	(60,910)	(61,856)
Time in Continuous Loss, Fair Value
12 Months or More Fair Value	363,970	339,235	363,970
Total Fair Value	363,970	$ 339,235	363,970
Collateralized Loan Obligations [Member]
Time in Continuous Loss, Unrealized Losses
Less Than 12 Months Unrealized Losses	(564)		(564)
12 Months or More Unrealized Losses	(1,496)		(1,496)
Total Unrealized Losses	(2,060)		(2,060)
Time in Continuous Loss, Fair Value
Less Than 12 Months, Fair Value	63,667		63,667
12 Months or More Fair Value	163,126		163,126
Total Fair Value	$ 226,793		$ 226,793