Revenue from Contract with Customers (Disaggregation by Timing of Revenue Recognition) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from contracts with customers		$ 45,930	$ 47,066	$ 47,989
Investment Advisory, Management and Administrative Service [Member]
Revenues from contracts with customers	[1]	36,848	38,341	39,346
Investment Advisory, Management and Administrative Service [Member] | Transferred over Time [Member]
Revenues from contracts with customers		36,848	38,341	39,346
Card Interchange Fees [Member]
Revenues from contracts with customers	[1]	4,214	3,768	3,502
Card Interchange Fees [Member] | Transferred at Point in Time [Member]
Revenues from contracts with customers		4,214	3,768	3,502
Deposit Account [Member]
Revenues from contracts with customers	[1]	3,684	3,628	3,672
Deposit Account [Member] | Transferred at Point in Time [Member]
Revenues from contracts with customers		2,850	2,802	2,899
Deposit Account [Member] | Transferred over Time [Member]
Revenues from contracts with customers		834	826	773
Other Noninterest Income [Member]
Revenues from contracts with customers	[1]	1,184	1,329	1,469
Other Noninterest Income [Member] | Transferred at Point in Time [Member]
Revenues from contracts with customers		989	958	1,122
Other Noninterest Income [Member] | Transferred over Time [Member]
Revenues from contracts with customers		$ 195	$ 371	$ 347

[1] Revenue from contracts with customers in scope of ASC 606.