Nature Of Operations and Significant Accounting Policies - Repossessed Assets and OREO (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Repossessed Assets
Repossessed assets	$ 0	$ 0
Other Real Estate Owned (OREO)
Beginning balance	8,666,000	8,760,000	$ 8,674,000
Additions		33,000	398,000
Deductions due to sales		(127,000)	(312,000)
Ending balance	8,666,000	$ 8,666,000	$ 8,760,000
Recent Accounting Pronouncements
Casualty brokerage income, employee benefit brokerage income and investment advisory income	18,300,000
Future operating lease obligations	$ 33,351,000