Securities, AFS Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	Jun. 30, 2021 USD ($) Position	Dec. 31, 2020 USD ($) Position
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 654,971	$ 213,643
12 months or longer	1,194	800
Total	656,165	214,443
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(8,534)	(2,170)
12 months or longer	(9)	(9)
Total	$ (8,543)	$ (2,179)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	75	19
12 months or longer | Position	5	4
Total | Position	80	23
AIR on AFS debt securities	$ 3,500	$ 3,300
Federal Agency [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	243,660	148,537
12 months or longer	0	0
Total	243,660	148,537
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(4,810)	(2,052)
12 months or longer	0	0
Total	$ (4,810)	$ (2,052)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	16	10
12 months or longer | Position	0	0
Total | Position	16	10
State & Municipal [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 42,038
12 months or longer	0
Total	42,038
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(480)
12 months or longer	0
Total	$ (480)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	27
12 months or longer | Position	0
Total | Position	27
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 250,767	$ 47,269
12 months or longer	774	800
Total	251,541	48,069
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(2,472)	(60)
12 months or longer	(8)	(9)
Total	$ (2,480)	$ (69)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	17	3
12 months or longer | Position	4	4
Total | Position	21	7
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 118,506	$ 17,837
12 months or longer	420	0
Total	118,926	17,837
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(772)	(58)
12 months or longer	(1)	0
Total	$ (773)	$ (58)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	15	6
12 months or longer | Position	1	0
Total | Position	16	6