Loans (Credit Quality Indicators - Residential, Consumer) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Current	$ 4,183,598	$ 3,877,310
Total Past Due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due	12,392	15,689
Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,456,973	1,437,661
Residential Real Estate [Member] | Total Past Due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due	10,339	11,429
Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current	257,518	288,178
Home Equity [Member] | Total Past Due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due	1,667	2,696
Other Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18,943	20,044
Other Consumer [Member] | Total Past Due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due	118	130
Total Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current	276,461	308,222
Total Consumer [Member] | Total Past Due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due	$ 1,785	$ 2,826