Investment Securities - Gross unrealized losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($)
Investment securities available-for-sale
Number of Holdings | security	129	183
Unrealized losses less than 12 months	$ (3)	$ (19,761)
Fair value less than 12 months	532	178,719
Unrealized losses over 12 months	(98,020)	(112,503)
Fair value over 12 months	485,527	535,024
Total Unrealized losses	(98,023)	(132,264)
Total Fair value	486,059	$ 713,743
Held-to-maturity investment securities
Number of Holdings | security		208
Unrealized losses less than 12 months		$ (3,336)
Fair value less than 12 months		18,788
Unrealized losses over 12 months		(47,654)
Fair value over 12 months		249,623
Total Unrealized losses		(50,990)
Total Fair value		268,411
Unrealized losses less than 12 months		(23,097)
Fair value less than 12 months		197,507
Unrealized losses over 12 months		(160,157)
Fair value over 12 months		$ 784,647
Total available for sale and held to maturity | security		391
Total Unrealized losses		$ (183,254)
Total Fair value		982,154
Held to Maturity, Excluding Accrued Interest, Past Due	0	0
Held-to-maturity interest income	$ 0	$ 0	$ 0
U.S. treasury and government agencies
Investment securities available-for-sale
Number of Holdings | security	1	1
Unrealized losses less than 12 months	$ (3)	$ (17)
Fair value less than 12 months	489	509
Total Unrealized losses	(3)	(17)
Total Fair value	$ 489	$ 509
Mortgage backed securities - Residential agency
Investment securities available-for-sale
Number of Holdings | security	112	145
Unrealized losses less than 12 months		$ (10,457)
Fair value less than 12 months	$ 43	79,693
Unrealized losses over 12 months	(88,547)	(107,711)
Fair value over 12 months	435,505	507,418
Total Unrealized losses	(88,547)	(118,168)
Total Fair value	$ 435,548	$ 587,111
Held-to-maturity investment securities
Number of Holdings | security		27
Unrealized losses over 12 months		$ (33,254)
Fair value over 12 months		150,861
Total Unrealized losses		(33,254)
Total Fair value		$ 150,861
Mortgage backed securities - Commercial
Investment securities available-for-sale
Number of Holdings | security	1	17
Unrealized losses less than 12 months		$ (4,835)
Fair value less than 12 months		50,437
Unrealized losses over 12 months	$ (123)	(2,276)
Fair value over 12 months	1,353	13,120
Total Unrealized losses	(123)	(7,111)
Total Fair value	$ 1,353	$ 63,557
Asset backed securities
Investment securities available-for-sale
Number of Holdings | security	3	3
Fair value less than 12 months		$ 32
Unrealized losses over 12 months	$ (1)
Fair value over 12 months	25	2
Total Unrealized losses	(1)
Total Fair value	$ 25	$ 34
Corporate bonds
Investment securities available-for-sale
Number of Holdings | security	12	17
Unrealized losses less than 12 months		$ (4,452)
Fair value less than 12 months		48,048
Unrealized losses over 12 months	$ (9,349)	(2,516)
Fair value over 12 months	48,644	14,484
Total Unrealized losses	(9,349)	(6,968)
Total Fair value	$ 48,644	62,532
Obligations of state and political agencies.
Investment securities available-for-sale
Unrealized losses less than 12 months		(3,336)
Fair value less than 12 months		18,788
Unrealized losses over 12 months		(14,400)
Fair value over 12 months		98,762
Total Unrealized losses		(17,736)
Total Fair value		$ 117,550
Held-to-maturity investment securities
Number of Holdings | security		181