Goodwill and Acquired Intangible Assets - Acquired Intangible Assets Consist of Core Deposit Intangibles (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 17,263	$ 9,494
Accumulated Amortization	(9,809)	(8,776)
Change the member lable Deposit Base [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	17,263	9,494
Accumulated Amortization	$ (9,809)	$ (8,776)