Derivative Financial Instruments - Free-Standing, Contingent Features and Counterparty Credit Risk (Details) - USD ($) $ in Thousands	12 Months Ended		96 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2015
Derivative financial instruments
Counterparty credit risk adjustments	$ 0	$ 200
Visa | Class B shares
Derivative financial instruments
Number of shares sold	274,000		0
Interest rate swaps | Maximum
Derivative financial instruments
Collateral thresholds for derivative agreements with credit risk related contingent features	$ 500
Derivatives Not Designated as Hedging Instruments | Interest rate swaps
Derivative financial instruments
Notional Amount	1,297,101	682,621	$ 682,621
Positive fair value, derivative asset	16,000	10,900	10,900
Fair value loss (derivative liability)	18,300	14,100	$ 14,100
Net interest expense on derivative	$ 1,100	$ 1,200
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Minimum
Derivative financial instruments
Fixed interest rate (as a percent)	0.77%	1.34%	1.34%
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Maximum
Derivative financial instruments
Fixed interest rate (as a percent)	4.90%	4.90%	4.90%
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Customer swap program
Derivative financial instruments
Notional Amount	$ 1,200,000	$ 652,600	$ 652,600
Upfront fees on the dealer swap	7,300	3,500
Derivative asset value	16,000	10,900	10,900
Derivative liability value	16,000	$ 10,900	$ 10,900
Derivatives Not Designated as Hedging Instruments | Funding Swap (Visa Derivative)
Derivative financial instruments
Notional Amount	37,143
Fair value loss (derivative liability)	$ 7,500