Derivatives and Hedging Activity - Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	$ 38,293	$ 89,361
Fair Value of Derivatives in a Liability Position	22,890	3,904
Derivatives designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	33	30
Fair Value of Derivatives in a Liability Position	2	56
Derivatives not designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	38,260	89,331
Fair Value of Derivatives in a Liability Position	22,888	3,848
Interest rate swaps | Derivatives designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	33	30
Fair Value of Derivatives in a Liability Position	2	56
Interest rate swaps | Derivatives not designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	23,961	26,591
Fair Value of Derivatives in a Liability Position		3,484
Foreign exchange contracts | Derivatives not designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	13,644	62,295
Fair Value of Derivatives in a Liability Position	22,888	364
Credit index instruments | Derivatives not designated as hedging instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	$ 655	$ 445