Financial Derivatives (Interest Rate Swaps) (Details) - Interest rate swaps - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Long
Derivative [Line Items]
Notional Amount	$ 438,560	$ 305,723
Fair Value	13,723	1,348
Long | 2021 [Member]
Derivative [Line Items]
Notional Amount	12,950	181,950
Fair Value	201	(49)
Long | 2022 [Member]
Derivative [Line Items]
Notional Amount	87,683	53,974
Fair Value	1,514	441
Long | 2023 [Member]
Derivative [Line Items]
Notional Amount	48,657	48,657
Fair Value	2,234	709
Long | 2024 [Member]
Derivative [Line Items]
Notional Amount	86,342	11,342
Fair Value	5,262	306
Long | 2025 [Member]
Derivative [Line Items]
Notional Amount	39,685
Fair Value	226
Long | 2027 [Member]
Derivative [Line Items]
Notional Amount	25,108
Fair Value	343
Long | 2029 [Member]
Derivative [Line Items]
Notional Amount	9,800	9,800
Fair Value	1,030	$ (59)
Long | 2030 [Member]
Derivative [Line Items]
Notional Amount	128,335
Fair Value	$ 2,913
Long | Weighted Average
Derivative [Line Items]
Pay Rate	1.25%	1.78%
Receive Rate	0.25%	1.91%
Remaining Years to Maturity	5 years 1 month 24 days	2 years 5 months 19 days
Long | Weighted Average | 2021 [Member]
Derivative [Line Items]
Pay Rate	1.75%	1.67%
Receive Rate	0.23%	1.89%
Remaining Years to Maturity	11 months 15 days	1 year 10 months 2 days
Long | Weighted Average | 2022 [Member]
Derivative [Line Items]
Pay Rate	1.33%	1.85%
Receive Rate	0.26%	1.91%
Remaining Years to Maturity	1 year 5 months 12 days	2 years 2 months 1 day
Long | Weighted Average | 2023 [Member]
Derivative [Line Items]
Pay Rate	2.00%	2.00%
Receive Rate	0.23%	1.92%
Remaining Years to Maturity	2 years 6 months 3 days	3 years 3 months 3 days
Long | Weighted Average | 2024 [Member]
Derivative [Line Items]
Pay Rate	1.65%	2.33%
Receive Rate	0.26%	2.09%
Remaining Years to Maturity	3 years 11 months 26 days	4 years 2 months 23 days
Long | Weighted Average | 2025 [Member]
Derivative [Line Items]
Pay Rate	0.44%
Receive Rate	0.24%
Remaining Years to Maturity	4 years 7 months 28 days
Long | Weighted Average | 2027 [Member]
Derivative [Line Items]
Pay Rate	0.63%
Receive Rate	0.30%
Remaining Years to Maturity	6 years 6 months
Long | Weighted Average | 2029 [Member]
Derivative [Line Items]
Pay Rate	1.78%	1.78%
Receive Rate	0.24%	1.91%
Remaining Years to Maturity	9 years 7 days	9 years 9 months 7 days
Long | Weighted Average | 2030 [Member]
Derivative [Line Items]
Pay Rate	0.90%
Receive Rate	0.25%
Remaining Years to Maturity	9 years 5 months 19 days
Short
Derivative [Line Items]
Notional Amount	$ 587,986	$ 732,961
Fair Value	(29,707)	(4,599)
Short | 2020 [Member]
Derivative [Line Items]
Notional Amount	17,500	68,607
Fair Value	(223)	(234)
Short | 2021 [Member]
Derivative [Line Items]
Notional Amount	129,975	268,929
Fair Value	(1,952)	(419)
Short | 2022 [Member]
Derivative [Line Items]
Notional Amount	146,012	31,350
Fair Value	(5,052)	9
Short | 2023 [Member]
Derivative [Line Items]
Notional Amount	31,500	101,012
Fair Value	(902)	(1,265)
Short | 2024 [Member]
Derivative [Line Items]
Notional Amount		13,000
Fair Value		99
Short | 2025 [Member]
Derivative [Line Items]
Notional Amount	28,104	12,800
Fair Value	(1,463)	(24)
Short | 2026 [Member]
Derivative [Line Items]
Notional Amount	34,000	59,902
Fair Value	(89)	1,946
Short | 2028 [Member]
Derivative [Line Items]
Notional Amount	32,942	32,942
Fair Value	(4,721)	(1,634)
Short | 2029 [Member]
Derivative [Line Items]
Notional Amount	92,594	136,838
Fair Value	(9,789)	(2,018)
Short | 2030 [Member]
Derivative [Line Items]
Notional Amount	68,463	685
Fair Value	(2,781)	(32)
Short | 2036 [Member]
Derivative [Line Items]
Notional Amount	1,100	1,100
Fair Value	(84)	87
Short | 2049 [Member]
Derivative [Line Items]
Notional Amount	5,796	5,796
Fair Value	$ (2,651)	$ (1,114)
Short | Weighted Average
Derivative [Line Items]
Pay Rate	1.43%	1.83%
Receive Rate	0.25%	1.94%
Remaining Years to Maturity	5 years 1 month 24 days	4 years 3 months 21 days
Short | Weighted Average | 2020 [Member]
Derivative [Line Items]
Pay Rate	2.75%	1.74%
Receive Rate	0.23%	1.93%
Remaining Years to Maturity	5 months 19 days	2 months 26 days
Short | Weighted Average | 2021 [Member]
Derivative [Line Items]
Pay Rate	1.21%	1.73%
Receive Rate	0.26%	1.95%
Remaining Years to Maturity	1 year 4 months 24 days	1 year 7 months 20 days
Short | Weighted Average | 2022 [Member]
Derivative [Line Items]
Pay Rate	1.50%	1.65%
Receive Rate	0.24%	1.93%
Remaining Years to Maturity	2 years 8 months 1 day	2 years 1 month 20 days
Short | Weighted Average | 2023 [Member]
Derivative [Line Items]
Pay Rate	0.95%	2.06%
Receive Rate	0.25%	1.91%
Remaining Years to Maturity	4 years 7 months 9 days	3 years 3 months 14 days
Short | Weighted Average | 2024 [Member]
Derivative [Line Items]
Pay Rate		1.56%
Receive Rate		1.89%
Remaining Years to Maturity		4 years 10 months 24 days
Short | Weighted Average | 2025 [Member]
Derivative [Line Items]
Pay Rate	1.25%
Receive Rate	0.22%
Remaining Years to Maturity	5 years 8 months 26 days	5 years 2 months 19 days
Short | Weighted Average | 2026 [Member]
Derivative [Line Items]
Pay Rate	0.49%	1.24%
Receive Rate	0.22%	1.94%
Remaining Years to Maturity	6 years 8 months 23 days	6 years 6 months
Short | Weighted Average | 2028 [Member]
Derivative [Line Items]
Pay Rate	2.40%	2.40%
Receive Rate	0.23%	1.93%
Remaining Years to Maturity	7 years 7 months 2 days	8 years 4 months 2 days
Short | Weighted Average | 2029 [Member]
Derivative [Line Items]
Pay Rate	1.78%	2.02%
Receive Rate	0.25%	1.96%
Remaining Years to Maturity	9 years 14 days	9 years 7 months 9 days
Short | Weighted Average | 2030 [Member]
Derivative [Line Items]
Pay Rate	1.10%	2.38%
Receive Rate	0.25%	1.90%
Remaining Years to Maturity	9 years 5 months 8 days	10 years 10 months 24 days
Short | Weighted Average | 2036 [Member]
Derivative [Line Items]
Pay Rate	1.45%	1.45%
Receive Rate	0.22%	1.94%
Remaining Years to Maturity	15 years 4 months 20 days	16 years 1 month 20 days
Short | Weighted Average | 2049 [Member]
Derivative [Line Items]
Pay Rate	2.89%	2.89%
Receive Rate	0.30%	2.09%
Remaining Years to Maturity	28 years 3 months 10 days	29 years 10 days
Forward-starting interest rate swap [Member] | Short
Derivative [Line Items]
Notional Amount		$ 20,900
Fair Value		$ (41)
Derivative fixed interest rate including forward-starting swaps		1.83%