Commitments, Contingencies and Derivatives (Summary of Contractual and Notional Amounts of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Home Equity Line of Credit [Member]
Financial Instruments [Line Items]
Contractual amounts of financial instrument	$ 477,401	$ 454,225
Commercial And Commercial Real Estate [Member]
Financial Instruments [Line Items]
Contractual amounts of financial instrument	49,482	83,103
Mortgage Loan Commitments [Member]
Financial Instruments [Line Items]
Contractual amounts of financial instrument	41,368	17,795
Letter of Credit [Member]
Financial Instruments [Line Items]
Contractual amounts of financial instrument	2,848	2,580
Other Commitments [Member]
Financial Instruments [Line Items]
Contractual amounts of financial instrument	523	432
Customer loan swaps
Financial Instruments [Line Items]
Notional amount of derivative	703,336	532,526
Forward-Starting Interest Rate Swap [Member]
Financial Instruments [Line Items]
Notional amount of derivative	50,000	50,000
Interest rate swaps
Financial Instruments [Line Items]
Notional amount of derivative	43,000	43,000
Interest Rate Lock Commitments [Member]
Financial Instruments [Line Items]
Notional amount of derivative	21,746	15,249
Forward Contracts [Member]
Financial Instruments [Line Items]
Notional amount of derivative	$ 8,065	$ 15,125