Fair Value Measurement - Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy (Details) - Fair Value, Measurements, Nonrecurring - USD ($)		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value on a nonrecurring basis		$ 0	$ 0
ASSETS
Loans held for sale	[1]	0	1,802,000
Impaired loans	[1]	11,407,000	10,329,000
Other real estate owned	[1]	718,000	396,000
Mortgage servicing rights	[1]	481,000	538,000
Total Assets	[1]	12,606,000	13,065,000
Level 1
ASSETS
Loans held for sale	[1]	0	0
Impaired loans	[1]	0	0
Other real estate owned	[1]	0	0
Mortgage servicing rights	[1]	0	0
Total Assets	[1]	0	0
Level 2
ASSETS
Loans held for sale	[1]	0	0
Impaired loans	[1]	0	0
Other real estate owned	[1]	0	0
Mortgage servicing rights	[1]	0	0
Total Assets	[1]	0	0
Level 3
ASSETS
Loans held for sale	[1]	0	1,802,000
Impaired loans	[1]	11,407,000	10,329,000
Other real estate owned	[1]	718,000	396,000
Mortgage servicing rights	[1]	481,000	538,000
Total Assets	[1]	$ 12,606,000	$ 13,065,000

[1] This table represents only the nonrecurring items that are recorded at fair value in our financial statements.