Fair Value of Financial Instruments - Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Impaired loans, with an allowance recorded, net	$ 18,838	$ 32,331
Mortgage servicing rights	5,789	18,918
Other real estate owned	20,371	35,491
Total assets at fair value	44,998	86,740
Level 1
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Impaired loans, with an allowance recorded, net	0	0
Mortgage servicing rights	0	0
Other real estate owned	0	0
Total assets at fair value	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Impaired loans, with an allowance recorded, net	0	0
Mortgage servicing rights	0	0
Other real estate owned	0	0
Total assets at fair value	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Impaired loans, with an allowance recorded, net	18,838	32,331
Mortgage servicing rights	5,789	18,918
Other real estate owned	20,371	35,491
Total assets at fair value	$ 44,998	$ 86,740