Commitments and Contingent Liabilities (Commitments to Extend Credit) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) request	Dec. 31, 2017 USD ($) request
Long-term Credit Commitments [Line Items]
Residential mortgage loans, repurchase obligation amount	$ 313	$ 238
Number of repurchase requests | request	0	0
Reserve for Off-balance Sheet Activities
Long-term Credit Commitments [Line Items]
Reserve for unfunded commitments	$ 172	$ 153
Commitments to Extend Credit
Long-term Credit Commitments [Line Items]
Commitments to extend credit, amount	2,470,000	1,960,000
Standby Letters of Credit
Long-term Credit Commitments [Line Items]
Commitments to extend credit, amount	$ 71,900	$ 55,500