Derivative Financial Instruments Derivative Financial Instruments - Schedule of Hedged Items Recorded in Statement of Financial Position (Details) - Deposits - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	$ (3,114,304)	$ (3,036,671)
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	$ 14,202	$ 22,168