Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 1,068,032	$ 977,830
Unrealized Gains	(35,766)	(43,354)
Unrealized Losses	(6,705)	(440)
Securities available-for-sale	1,097,093	1,020,744
US Government Agencies Debt Securities [Member]
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	95,361	92,710
Unrealized Gains	(3,676)	(5,105)
Unrealized Losses	(95)	(1)
Securities available-for-sale	98,942	97,814
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	447,454	346,606
Unrealized Gains	(7,162)	(8,794)
Unrealized Losses	(5,137)	(279)
Securities available-for-sale	449,479	355,121
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	15,808	17,931
Unrealized Gains	(440)	(559)
Unrealized Losses	0	0
Securities available-for-sale	16,248	18,490
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	179,460	209,556
Unrealized Gains	(3,975)	(4,761)
Unrealized Losses	(174)	(157)
Securities available-for-sale	183,261	214,160
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	305,159	285,837
Unrealized Gains	(16,976)	(20,294)
Unrealized Losses	(892)	0
Securities available-for-sale	321,243	306,131
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	0	0
Unrealized Gains	(3,328)	(3,136)
Unrealized Losses	0	0
Securities available-for-sale	$ 3,328	$ 3,136