Mergers and Acquisitions - BOA Branch Acquisition - (Details) $ in Thousands	Aug. 21, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Deposits:
Goodwill		$ 338,340	$ 317,688	$ 317,688
Bank of America
Mergers and Acquisitions
Percentage of average daily deposits for thirty day period	5.5
Business Combination Recognized Identifiable Assets Acquired
Cash and cash equivalents	$ 428,567
Loans	3,150
Premises and equipment	4,129
Intangible assets	6,800
Other assets	66
Total assets	442,712
Deposits:
Noninterest-bearing	97,440
Interest-bearing	340,849
Total deposits	438,289
Other liabilities	56
Total liabilities	438,345
Net identifiable assets acquired over (under) liabilities assumed	4,367
Goodwill	20,652
Net assets acquired over liabilities assumed	25,019
Consideration:
Business combination deposit premium paid	25,019
Fair value of total consideration transferred	25,019
Bank of America | As previously recorded by acquiree
Business Combination Recognized Identifiable Assets Acquired
Cash and cash equivalents	428,567
Loans	3,445
Premises and equipment	6,267
Other assets	66
Total assets	438,345
Deposits:
Noninterest-bearing	97,440
Interest-bearing	340,849
Total deposits	438,289
Other liabilities	56
Total liabilities	438,345
Bank of America | Fair Value Adjustments
Business Combination Recognized Identifiable Assets Acquired
Loans	(295)
Premises and equipment	(2,138)
Intangible assets	6,800
Total assets	4,367
Deposits:
Net identifiable assets acquired over (under) liabilities assumed	4,367
Goodwill	20,652
Net assets acquired over liabilities assumed	$ 25,019