Other Comprehensive (Loss) Income (Components of OCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Unrealized gains and losses on available for sale debt securities:
Net unrealized (losses) gains arising during the period	$ (1,252)	$ 13,281	$ 21,310	$ 23,698
Reclassification adjustment for gains included in net income	0	0	0	0
Total	(1,252)	13,281	21,310	23,698
Unrealized losses on derivatives (cash flow hedges)	(1,730)	(874)	(9,427)	(1,306)
Amortization related to post-retirement obligations	95	47	207	30
Total other comprehensive (loss) income	(2,887)	12,454	12,090	22,422
Unrealized gains and losses on available for sale debt securities:
Net unrealized (losses) gains arising during the period	322	(3,619)	(5,494)	(6,458)
Reclassification adjustment for gains included in net income	0	0	0	0
Total	322	(3,619)	(5,494)	(6,458)
Unrealized losses on derivatives (cash flow hedges)	446	238	2,430	356
Amortization related to post-retirement obligations	(25)	(13)	(53)	(8)
Total other comprehensive (loss) income	743	(3,394)	(3,117)	(6,110)
Unrealized gains and losses on available for sale debt securities:
Net unrealized (losses) gains arising during the period	(930)	9,662	15,816	17,240
Reclassification adjustment for gains included in net income	0	0	0	0
Total	(930)	9,662	15,816	17,240
Unrealized losses on derivatives (cash flow hedges)	(1,284)	(636)	(6,997)	(950)
Amortization related to post-retirement obligations	70	34	154	22
Total other comprehensive (loss) income	$ (2,144)	$ 9,060	$ 8,973	$ 16,312