Borrowed Funds (Details) - Unused Short-Term Credit Lines Available for Use - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
FRBs Discount Window Primary Credit Program
Line of Credit Facility [Line Items]
Amount outstanding	$ 629,699	$ 655,745
Available federal funds lines
Line of Credit Facility [Line Items]
Amount outstanding	632,000	659,000
Correspondent bank line of credit
Line of Credit Facility [Line Items]
Amount outstanding	$ 50,000	$ 0