Loans (Credit Quality Indicators - Residential, Consumer) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Current	$ 3,723,769	$ 3,666,738
Total past due	14,700	13,622
Self-originated Mortgages
Financing Receivable, Recorded Investment [Line Items]
Current	1,240,306	1,238,402
Total past due	9,751	9,079
Purchased Mortgages
Financing Receivable, Recorded Investment [Line Items]
Current	107,917	111,465
Total past due	1,098	1,441
Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	1,348,223	1,349,867
Total past due	10,849	10,520
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Current	277,027	278,637
Total past due	2,911	1,989
Other
Financing Receivable, Recorded Investment [Line Items]
Current	25,156	26,202
Total past due	13	33
Total Consumer
Financing Receivable, Recorded Investment [Line Items]
Current	302,183	304,839
Total past due	$ 2,924	$ 2,022