Loans (Credit Quality Indicators - Residential, Consumer) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Current	$ 3,763,750	$ 3,666,738
Total past due	14,356	13,622
Self-originated Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,261,364	1,238,402
Total past due	10,503	9,079
Purchased Mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current	105,555	111,465
Total past due	1,096	1,441
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,366,919	1,349,867
Total past due	11,599	10,520
Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Current	292,277	278,637
Total past due	1,973	1,989
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current	21,493	26,202
Total past due	99	33
Total Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current	313,770	304,839
Total past due	$ 2,072	$ 2,022