Accumulated Other Comprehensive Loss (Components of Comprehensive Income) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Available for sale securities - all other: Net unrealized losses on all other AFS securities, Net of tax $ (230) $ 1,708 $ (1,308) $ 1,786
Cash flow hedges: Unrealized holding gains, Before Tax 148 (249) 755 (163)
Cash flow hedges: Unrealized holding gains, Tax Effect (40) 99 (204) 65
Cash flow hedges: Unrealized holding gains, Net of Tax 108 (150) 551 (98)
Unrealized net actuarial gain (loss), Net of Tax (1,530) 2 (794) 196
Less: amortization of unrecognized net gain (loss), Before Tax   (36)    
Less: amortization of unrecognized net gain (loss), Tax Effect   15    
Less: amortization of unrecognized net gain (loss), Net of Tax   (21)    
Other comprehensive income, Before tax amount     248 3,419
Other comprehensive income, Tax (expense) benefit     (68) (1,368)
Other comprehensive income, Net     180 2,063
Investment securities- with OTTI [Member]        
Available for sale (AFS) securities with OTTI: Unrealized holding gains, Before tax amount 1,493 (56) 2,432 110
Available for sale (AFS) securities with OTTI: Unrealized holding gains, Tax effect (404) 23 (658) (44)
Available for sale (AFS) securities with OTTI: Unrealized holding gains, Net of tax 1,089 (33) 1,774 66
Available for sale (AFS) securities with OTTI: Less: accretable yield recognized in income 52 55 107 57
Available for sale (AFS) securities with OTTI: Less: accretable yield recognized in income, Tax effect (14) (22) (29) (23)
Other than temporary impairment losses, investments, reclassification adjustment of noncredit portion included in net income, Available for sale securities, Net of tax 38 33 78 34
Available for sale (AFS) securities with OTTI: Net unrealized gains on investments with OTTI, Before tax amount 1,296 (111) 2,180 53
Available for sale (AFS) securities with OTTI: Net unrealized gains on investments with OTTI, Tax effect (351) 45 (590) (21)
Available for sale (AFS) securities with OTTI: Net unrealized gains on investments with OTTI, Net of tax 945 (66) 1,590 32
Investment Securities -All Other AFS [Member]        
Securities: Unrealized holding losses, Before tax (325) 2,832 (1,812) 2,954
Securities: Unrealized holding losses, Tax effect 88 (1,129) 490 (1,178)
Securities: Unrealized holding losses, Net of tax (237) 1,703 (1,322) 1,776
Securities: Less: gains recognized in income, Before tax (10) (8) (19) (17)
Securities: Less: gains recognized in income, Tax effect 3 3 5 7
Securities: gains recognized in income, Net of tax (7) (5) (14) (10)
Available for sale securities: Net unrealized losses on all other AFS securities, Before Tax (315) 2,840 (1,793) 2,971
Available for sale securities: Net unrealized losses on all other AFS securities, Tax effect 85 (1,132) 485 (1,185)
Available for sale securities - all other: Net unrealized losses on all other AFS securities, Net of tax (230) 1,708 (1,308) 1,786
Investment Securities HTM [Member]        
Securities: Unrealized holding losses, Before tax 0 0 0 0
Securities: Unrealized holding losses, Tax effect 0 0 0 0
Securities: Unrealized holding losses, Net of tax 0 0 0 0
Securities: Less: gains recognized in income, Before tax (52) (71) (114) (172)
Securities: Less: gains recognized in income, Tax effect 14 28 31 68
Securities: gains recognized in income, Net of tax (38) (43) (83) (104)
Held to maturity securities: Net unrealized losses on all HTM securities, Before tax 52 71 114 172
Held to maturity securities: Net unrealized losses on all HTM securities, Tax (14) (28) (31) (68)
Held to maturity securities: Net unrealized losses on all HTM securities, After tax 38 43 83 104
Pension Plan [Member]        
Unrealized net actuarial gain (loss), Before Tax (2,399) (261) (1,692) (208)
Unrealized net actuarial gain (loss), Tax Effect 648 103 457 82
Unrealized net actuarial gain (loss), Net of Tax (1,751) (158) (1,235) (126)
Less: amortization of unrecognized net gain (loss), Before Tax (300) (264)    
Less: amortization of unrecognized net gain (loss), Tax Effect 81 105    
Less: amortization of unrecognized net gain (loss), Net of Tax (219) (159)    
Less: amortization of prior service costs, Before Tax (2) (3)    
Less: amortization of prior service costs, Tax Effect 0 2    
Less: amortization of prior service costs, Net of Tax (2) (1)    
Net plan liability adjustment, Before Tax (2,097) 6 (1,088) 314
Net plan liability adjustment, Tax Effect 567 (4) 294 (130)
Net plan liability adjustment, Net of Tax (1,530) 2 (794) 196
SERP [Member]        
Unrealized net actuarial gain (loss), Before Tax 0 0 0 0
Unrealized net actuarial gain (loss), Tax Effect 0 0 0 0
Unrealized net actuarial gain (loss), Net of Tax 0 0 0 0
Less: amortization of unrecognized net gain (loss), Before Tax (40)      
Less: amortization of unrecognized net gain (loss), Tax Effect 11      
Less: amortization of unrecognized net gain (loss), Net of Tax (29)      
Less: amortization of prior service costs, Before Tax 0 0    
Less: amortization of prior service costs, Tax Effect 0 0    
Less: amortization of prior service costs, Net of Tax 0 0    
Net plan liability adjustment, Before Tax 40 36 80 72
Net plan liability adjustment, Tax Effect (11) (15) (22) (29)
Net plan liability adjustment, Net of Tax 29 21 58 43
Other comprehensive income, Before tax amount (876) 2,593    
Other comprehensive income, Tax (expense) benefit 236 (1,035)    
Other comprehensive income, Net $ (640) $ 1,558    
Amortization of unrecognized loss [Member] | Pension Plan [Member]        
Less: amortization of unrecognized net gain (loss), Before Tax     (600) (528)
Less: amortization of unrecognized net gain (loss), Tax Effect     162 210
Less: amortization of unrecognized net gain (loss), Net of Tax     (438) (318)
Amortization of Unrecognized Gain [Member] | SERP [Member]        
Less: amortization of unrecognized net gain (loss), Before Tax     (81) (73)
Less: amortization of unrecognized net gain (loss), Tax Effect     22 29
Less: amortization of unrecognized net gain (loss), Net of Tax     (59) (44)
Amortization of prior service costs [Member] | Pension Plan [Member]        
Less: amortization of prior service costs, Before Tax     (4) (6)
Less: amortization of prior service costs, Tax Effect     1 2
Less: amortization of prior service costs, Net of Tax     (3) (4)
Amortization of prior service costs [Member] | SERP [Member]        
Less: amortization of prior service costs, Before Tax     1 1
Less: amortization of prior service costs, Tax Effect     0 0
Less: amortization of prior service costs, Net of Tax     $ 1 $ 1