Derivative Financial Instruments - Notional Amounts and Fair Values (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivatives designated as hedging instruments | Interest rate swaps
Notional amounts and fair values of derivatives
Notional Amount	$ 193,022	$ 194,687
Derivatives designated as hedging instruments | Interest rate swaps | Included in other assets
Notional amounts and fair values of derivatives
Asset Derivatives	266
Derivatives designated as hedging instruments | Interest rate swaps | Included in other liabilities
Notional amounts and fair values of derivatives
Liability Derivatives	(312)	(2,032)
Derivatives Not Designated as Hedging Instruments | Interest rate swaps
Notional amounts and fair values of derivatives
Notional Amount	2,156,450	1,820,442
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Included in other assets
Notional amounts and fair values of derivatives
Asset Derivatives	5,117	14,658
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Included in other liabilities
Notional amounts and fair values of derivatives
Liability Derivatives	(22,932)	(13,017)
Derivatives Not Designated as Hedging Instruments | Funding Swap (Visa Derivative)
Notional amounts and fair values of derivatives
Notional Amount	58,237	43,113
Derivatives Not Designated as Hedging Instruments | Funding Swap (Visa Derivative) | Included in other liabilities
Notional amounts and fair values of derivatives
Liability Derivatives	(4,114)	(5,439)
Derivatives Not Designated as Hedging Instruments | Foreign exchange contracts
Notional amounts and fair values of derivatives
Notional Amount	4,801	3,658
Derivatives Not Designated as Hedging Instruments | Foreign exchange contracts | Included in other assets
Notional amounts and fair values of derivatives
Asset Derivatives	1	$ 24
Derivatives Not Designated as Hedging Instruments | Foreign exchange contracts | Included in other liabilities
Notional amounts and fair values of derivatives
Liability Derivatives	$ (69)