Goodwill and Other Amortizing Intangible Assets - Estimated Amortization Expense of Core Deposit Intangibles (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Other Intangibles [Line Items]
2016	$ 2,262
2017	2,022
2018	1,786
2019	1,502
2020	1,279
Thereafter	3,162
Net Intangible Assets	12,013	$ 1,231
Customer list intangible
Goodwill And Other Intangibles [Line Items]
2016	129
2017	99
2018	77
2019	59
2020	45
Thereafter	131
Net Intangible Assets	540	$ 708
Customer deposit intangibles
Goodwill And Other Intangibles [Line Items]
2016	2,133
2017	1,923
2018	1,709
2019	1,443
2020	1,234
Thereafter	3,031
Net Intangible Assets	$ 11,473