Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 914,362	$ 907,575
Unrealized Gains	(42,469)	(20,976)
Unrealized Losses	(592)	(1,834)
Securities available-for-sale	956,239	926,717
US Government Agencies Debt Securities [Member]
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	94,924	102,490
Unrealized Gains	(5,430)	(1,293)
Unrealized Losses	(4)	(150)
Securities available-for-sale	100,350	103,633
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	276,182	240,753
Unrealized Gains	(8,710)	(2,979)
Unrealized Losses	(282)	(350)
Securities available-for-sale	284,610	243,382
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	18,046	22,036
Unrealized Gains	(634)	(73)
Unrealized Losses	0	(5)
Securities available-for-sale	18,680	22,104
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	225,964	280,797
Unrealized Gains	(5,821)	(1,735)
Unrealized Losses	(217)	(1,221)
Securities available-for-sale	231,568	281,311
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	276,640	253,277
Unrealized Gains	(18,200)	(11,265)
Unrealized Losses	(86)	(108)
Securities available-for-sale	294,754	264,434
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	0	0
Unrealized Gains	(3,036)	(3,619)
Unrealized Losses	0	0
Securities available-for-sale	$ 3,036	$ 3,619