Loans (Credit Quality Indicators Vintage) (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	$ 203,818
Term loans amortized cost, prior year	668,433
Term loans amortized cost, two years ago	649,933
Term loans amortized cost, three years ago	592,527
Term loans amortized cost, four years ago	384,859
Term loans amortized cost, five years ago or more	1,184,128
Revolving loans amortized cost	387,636
Revolving loans converted to term loans	19,062
Total	4,090,396
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	55,517
Term loans amortized cost, prior year	235,636
Term loans amortized cost, two years ago	340,015
Term loans amortized cost, three years ago	287,171
Term loans amortized cost, four years ago	157,491
Term loans amortized cost, five years ago or more	532,228
Revolving loans amortized cost	7,445
Revolving loans converted to term loans	2,517
Total	1,618,020
Commercial Real Estate | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	55,517
Term loans amortized cost, prior year	235,636
Term loans amortized cost, two years ago	340,015
Term loans amortized cost, three years ago	277,871
Term loans amortized cost, four years ago	157,491
Term loans amortized cost, five years ago or more	530,953
Revolving loans amortized cost	7,445
Revolving loans converted to term loans	2,517
Total	1,607,445
Commercial Real Estate | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	9,300
Term loans amortized cost, four years ago	0
Term loans amortized cost, five years ago or more	825
Revolving loans amortized cost	0
Revolving loans converted to term loans	0
Total	10,125
Commercial Real Estate | Classified [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	0
Term loans amortized cost, four years ago	0
Term loans amortized cost, five years ago or more	450
Revolving loans amortized cost	0
Revolving loans converted to term loans	0
Total	450
Commercial & Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	43,850
Term loans amortized cost, prior year	80,561
Term loans amortized cost, two years ago	59,753
Term loans amortized cost, three years ago	72,240
Term loans amortized cost, four years ago	47,241
Term loans amortized cost, five years ago or more	214,817
Revolving loans amortized cost	135,030
Revolving loans converted to term loans	1,665
Total	655,157
Commercial & Industrial | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	43,850
Term loans amortized cost, prior year	80,561
Term loans amortized cost, two years ago	59,753
Term loans amortized cost, three years ago	70,374
Term loans amortized cost, four years ago	43,616
Term loans amortized cost, five years ago or more	189,242
Revolving loans amortized cost	130,463
Revolving loans converted to term loans	1,599
Total	619,458
Commercial & Industrial | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	1,866
Term loans amortized cost, four years ago	3,625
Term loans amortized cost, five years ago or more	17,229
Revolving loans amortized cost	2,128
Revolving loans converted to term loans	66
Total	24,914
Commercial & Industrial | Classified [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	0
Term loans amortized cost, four years ago	0
Term loans amortized cost, five years ago or more	8,346
Revolving loans amortized cost	2,439
Revolving loans converted to term loans	0
Total	10,785
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	100,890
Term loans amortized cost, prior year	339,953
Term loans amortized cost, two years ago	242,630
Term loans amortized cost, three years ago	228,217
Term loans amortized cost, four years ago	177,616
Term loans amortized cost, five years ago or more	421,166
Revolving loans amortized cost	0
Revolving loans converted to term loans	0
Total	1,510,472
Residential Real Estate | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	100,890
Term loans amortized cost, prior year	339,675
Term loans amortized cost, two years ago	241,997
Term loans amortized cost, three years ago	225,108
Term loans amortized cost, four years ago	177,100
Term loans amortized cost, five years ago or more	413,409
Revolving loans amortized cost	0
Revolving loans converted to term loans	0
Total	1,498,179
Residential Real Estate | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	278
Term loans amortized cost, two years ago	633
Term loans amortized cost, three years ago	3,109
Term loans amortized cost, four years ago	516
Term loans amortized cost, five years ago or more	7,757
Revolving loans amortized cost	0
Revolving loans converted to term loans	0
Total	12,293
Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	2,947
Term loans amortized cost, prior year	9,308
Term loans amortized cost, two years ago	5,510
Term loans amortized cost, three years ago	2,578
Term loans amortized cost, four years ago	1,601
Term loans amortized cost, five years ago or more	5,566
Revolving loans amortized cost	244,747
Revolving loans converted to term loans	14,877
Total	287,134
Home Equity | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	2,947
Term loans amortized cost, prior year	9,308
Term loans amortized cost, two years ago	5,510
Term loans amortized cost, three years ago	2,528
Term loans amortized cost, four years ago	1,601
Term loans amortized cost, five years ago or more	5,473
Revolving loans amortized cost	243,986
Revolving loans converted to term loans	13,299
Total	284,652
Home Equity | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	0
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	50
Term loans amortized cost, four years ago	0
Term loans amortized cost, five years ago or more	93
Revolving loans amortized cost	761
Revolving loans converted to term loans	1,578
Total	2,482
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	614
Term loans amortized cost, prior year	2,975
Term loans amortized cost, two years ago	2,025
Term loans amortized cost, three years ago	2,321
Term loans amortized cost, four years ago	910
Term loans amortized cost, five years ago or more	10,351
Revolving loans amortized cost	414
Revolving loans converted to term loans	3
Total	19,613
Other | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	605
Term loans amortized cost, prior year	2,975
Term loans amortized cost, two years ago	2,025
Term loans amortized cost, three years ago	2,321
Term loans amortized cost, four years ago	822
Term loans amortized cost, five years ago or more	10,334
Revolving loans amortized cost	414
Revolving loans converted to term loans	2
Total	19,498
Other | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans amortized cost, current year	9
Term loans amortized cost, prior year	0
Term loans amortized cost, two years ago	0
Term loans amortized cost, three years ago	0
Term loans amortized cost, four years ago	88
Term loans amortized cost, five years ago or more	17
Revolving loans amortized cost	0
Revolving loans converted to term loans	1
Total	$ 115