Goodwill and Identifiable Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Future amortization expense for identifiable intangible assets [Abstract]
Goodwill from purchase of insurance book of business	$ 656,000
Impairment charge	0
Amortization expense of identifiable intangible assets	7,800,000	$ 8,800,000	$ 8,800,000
2016	6,900,000
2017	5,900,000
2018	4,900,000
2019	3,800,000
2020	2,500,000
Impairment losses on identifiable intangible assets	0	0	0
Insurance [Member]
Future amortization expense for identifiable intangible assets [Abstract]
Goodwill from purchase of insurance book of business	656,000	656,000	656,000
General Banking And Insurance [Member]
Future amortization expense for identifiable intangible assets [Abstract]
Impairment charge	$ 0	0	$ 0
BancTrust acquisition [Member]
Future amortization expense for identifiable intangible assets [Abstract]
Goodwill decreased as a result of fair value adjustment		$ 7,400,000