Fair Value Measurements - Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
ASSETS
Loans held for sale	$ 2,900
Impaired loans	13,913	$ 12,916
Other Assets, Fair Value Disclosure	747	117
Mortgage servicing rights	721	1,176
Total Assets	18,281	14,209
Level 3 [Member]
ASSETS
Loans held for sale	2,900
Impaired loans	13,913	12,916
Other Assets, Fair Value Disclosure	747	117
Mortgage servicing rights	721	1,176
Total Assets	$ 18,281	$ 14,209