Loans (Credit Quality Indicators - Residential, Consumer) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Current	$ 4,272,969	$ 3,877,310
Total past due	14,672	15,689
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,495,724	1,437,661
Total past due	12,499	11,429
Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Current	275,999	288,178
Total past due	1,633	2,696
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18,237	20,044
Total past due	106	130
Total Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current	294,236	308,222
Total past due	$ 1,739	$ 2,826