Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 895,703	$ 907,575
Unrealized Gains	(36,784)	(20,976)
Unrealized Losses	(446)	(1,834)
Securities available-for-sale	932,041	926,717
US Government Agencies Debt Securities [Member]
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	98,780	102,490
Unrealized Gains	(2,762)	(1,293)
Unrealized Losses	(38)	(150)
Securities available-for-sale	101,504	103,633
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	235,774	240,753
Unrealized Gains	(9,082)	(2,979)
Unrealized Losses	0	(350)
Securities available-for-sale	244,856	243,382
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	21,891
Unrealized Gains	(798)
Unrealized Losses	0
Securities available-for-sale	22,689	22,104
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	276,125	280,797
Unrealized Gains	(8,461)	(1,735)
Unrealized Losses	(220)	(1,221)
Securities available-for-sale	284,366	281,311
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	259,907	253,277
Unrealized Gains	(12,410)	(11,265)
Unrealized Losses	(188)	(108)
Securities available-for-sale	272,129	264,434
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	0	0
Unrealized Gains	(3,233)	(3,619)
Unrealized Losses	0	0
Securities available-for-sale	$ 3,233	$ 3,619