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Securities, Available for Sale (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt securities, available-for-sale [Abstract]
Amortized cost	$ 1,164,633		$ 1,164,633		$ 968,554
Unrealized gains	33,850		33,850		8,319
Unrealized losses	558		558		1,533
Estimated fair value	1,197,925		1,197,925		975,340
Allowance for credit losses on AFS securities	0		0
Sales transactions of securities available for sale [Abstract]
Gross realized gains	0	$ 20	3	$ 73
Gross realized (losses)	0	0	0	(152)
Net AFS realized gains (losses)	0	20	3	(79)
Gains from calls on securities available for sale	0	$ 20	3	$ 25
Federal Agency [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	195,588		195,588		34,998
Unrealized gains	97		97		3
Unrealized losses	541		541		243
Estimated fair value	195,144		195,144		34,758
State & Municipal [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	10,712		10,712		2,533
Unrealized gains	173		173		0
Unrealized losses	2		2		20
Estimated fair value	10,883		10,883		2,513
Mortgage-Backed, Government Sponsored Enterprises [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	406,495		406,495		453,614
Unrealized gains	18,216		18,216		4,982
Unrealized losses	0		0		239
Estimated fair value	424,711		424,711		458,357
Mortgage-Backed, U.S. Government Agency Securities [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	55,259		55,259		44,758
Unrealized gains	2,358		2,358		667
Unrealized losses	9		9		156
Estimated fair value	57,608		57,608		45,269
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	350,114		350,114		328,499
Unrealized gains	8,539		8,539		1,949
Unrealized losses	2		2		467
Estimated fair value	358,651		358,651		329,981
Collateralized Mortgage Obligations, U.S. Government Agency Securities [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	128,965		128,965		104,152
Unrealized gains	4,136		4,136		718
Unrealized losses	0		0		408
Estimated fair value	133,101		133,101		$ 104,462
Corporate [Member]
Debt securities, available-for-sale [Abstract]
Amortized cost	17,500		17,500
Unrealized gains	331		331
Unrealized losses	4		4
Estimated fair value	$ 17,827		$ 17,827

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