Intangible Assets and Goodwill - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Weighted-average life		7 years 7 months 6 days
Impairment loss		$ 368
Community Banks [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment loss		$ 368
Community Banks [Member] | Other Noninterest Expense [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment loss	$ 368
Customer Related Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life		7 years 9 months 18 days
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life		7 years 7 months 6 days
Mortgage Servicing Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life		2 years