Loans (Credit Quality Indicators - Residential, Consumer) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Current	$ 3,473,535	$ 3,353,996
Total past due	16,695	20,075
Self-originated Mortgages
Financing Receivable, Recorded Investment [Line Items]
Current	1,194,914	1,091,291
Total past due	10,012	6,413
Purchased Mortgages
Financing Receivable, Recorded Investment [Line Items]
Current	121,261	128,102
Total past due	1,231	1,442
Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Current	1,316,175	1,219,393
Total past due	11,243	7,855
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Current	281,159	289,326
Total past due	2,585	3,141
Other
Financing Receivable, Recorded Investment [Line Items]
Current	28,380	31,484
Total past due	16	43
Total Consumer
Financing Receivable, Recorded Investment [Line Items]
Current	309,539	320,810
Total past due	$ 2,601	$ 3,184