Fair Value Measurement - Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
ASSETS
Loans held for sale	[1]	$ 216
Impaired loans	[1]	8,870	$ 12,916
Other real estate owned	[1]	439	117
Mortgage servicing rights	[1]	1,827	2,934
Total Assets	[1]	11,352	15,967
Level 3 [Member]
ASSETS
Loans held for sale	[1]	216
Impaired loans	[1]	8,870	12,916
Other real estate owned	[1]	439	117
Mortgage servicing rights	[1]	1,827	2,934
Total Assets	[1]	$ 11,352	$ 15,967

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