Investment Securities - Fair Value of Investments with Sustained Gross Unrealized Losses (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	$ 948,129,000	$ 680,526,000
Available-for-sale, Less than 12 months, Unrealized Losses	(129,854,000)	(13,708,000)
Available-for-sale, 12 months or longer, Fair Value	310,522,000	186,350,000
Available-for-sale, 12 months or longer, Unrealized losses	(51,516,000)	(4,627,000)
Available-for-sale, Total Fair Value	1,258,651,000	866,876,000
Available-for-sale, Total Unrealized Losses	(181,370,000)	(18,335,000)
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	121,758,000	48,316,000
Available-for-sale, Less than 12 months, Unrealized Losses	(8,930,000)	(1,927,000)
Available-for-sale, 12 months or longer, Fair Value	111,991,000	139,846,000
Available-for-sale, 12 months or longer, Unrealized losses	(15,618,000)	(2,936,000)
Available-for-sale, Total Fair Value	233,749,000	188,162,000
Available-for-sale, Total Unrealized Losses	(24,548,000)	(4,863,000)
Obligations of States and Political Subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	253,771,000	61,535,000
Available-for-sale, Less than 12 months, Unrealized Losses	(55,918,000)	(657,000)
Available-for-sale, 12 months or longer, Fair Value	7,466,000	0
Available-for-sale, 12 months or longer, Unrealized losses	(2,626,000)	0
Available-for-sale, Total Fair Value	261,237,000	61,535,000
Available-for-sale, Total Unrealized Losses	(58,544,000)	(657,000)
Mortgage-backed Securities: GSE Residential
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	505,673,000	562,699,000
Available-for-sale, Less than 12 months, Unrealized Losses	(62,477,000)	(11,019,000)
Available-for-sale, 12 months or longer, Fair Value	188,576,000	46,504,000
Available-for-sale, 12 months or longer, Unrealized losses	(33,196,000)	(1,691,000)
Available-for-sale, Total Fair Value	694,249,000	609,203,000
Available-for-sale, Total Unrealized Losses	(95,673,000)	(12,710,000)
Other Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	66,927,000	7,976,000
Available-for-sale, Less than 12 months, Unrealized Losses	(2,529,000)	(105,000)
Available-for-sale, 12 months or longer, Fair Value	2,489,000	0
Available-for-sale, 12 months or longer, Unrealized losses	(76,000)	0
Available-for-sale, Total Fair Value	69,416,000	7,976,000
Available-for-sale, Total Unrealized Losses	$ (2,605,000)	$ (105,000)