Fair Value Measurement - Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy (Detail) - Fair Value, Measurements, Nonrecurring - USD ($)		Sep. 30, 2016	Dec. 31, 2015
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
Impaired loans	[1]	9,000,000	9,373,000
Other real estate owned	[1]	181,000	158,000
Mortgage servicing rights	[1]	3,253,000	3,396,000
Total Assets	[1]	12,434,000	12,927,000
Level 1
ASSETS
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
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
Impaired loans	[1]	9,000,000	9,373,000
Other real estate owned	[1]	181,000	158,000
Mortgage servicing rights	[1]	3,253,000	3,396,000
Total Assets	[1]	$ 12,434,000	$ 12,927,000

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