Derivative Financial Instruments - Free-Standing (Details) $ in Thousands	12 Months Ended				96 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Oct. 31, 2019 USD ($)	Sep. 27, 2019	Jul. 31, 2018 USD ($)	Jun. 28, 2018
Visa | Class B restricted shares
Derivative financial instruments
Estimated liability that was subsequently paid to the buyer						$ 300
Number of shares sold | shares				274,000	0
Other noninterest income | Visa
Derivative financial instruments
Loss related to a revaluation adjustment to increase the fair value	$ 4,500
Interest rate swaps | Customer swap program
Derivative financial instruments
Notional Amount	2,800,000
Funding Swap (Visa Derivative) | Class B restricted shares
Derivative financial instruments
Conversion rate			1.6483				1.6228		1.6298
Funding Swap (Visa Derivative) | Visa
Derivative financial instruments
Conversion rate			1.6483				1.6228		1.6298
Estimated liability that was subsequently paid to the buyer								$ 700
Funding Swap (Visa Derivative) | Included in other liabilities
Derivative financial instruments
Derivative liability value	4,200	$ 2,600
Derivatives Not Designated as Hedging Instruments | Interest rate swaps
Derivative financial instruments
Notional Amount	2,818,803	2,269,247
Net interest expense on derivative	$ 0	$ 500	$ 900
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Minimum
Derivative financial instruments
Fixed interest rate (as a percent)	1.71%	2.02%
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Maximum
Derivative financial instruments
Fixed interest rate (as a percent)	8.73%	5.78%
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Customer swap program
Derivative financial instruments
Notional Amount		$ 2,200,000
Positive fair value, derivative asset		12,300
Negative fair value, derivative liability		12,000
Derivative asset value	$ 63,500	12,300
Derivative liability value	0	11,200
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Customer swap program | Maximum
Derivative financial instruments
Positive fair value, derivative asset	63,500
Negative fair value, derivative liability
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Customer swap program | Other noninterest income
Derivative financial instruments
Upfront fees on the dealer swap	4,500	7,300	$ 6,700
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Included in other assets
Derivative financial instruments
Positive fair value, derivative asset	63,527	12,305
Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Included in other liabilities
Derivative financial instruments
Negative fair value, derivative liability		12,007
Derivatives Not Designated as Hedging Instruments | Funding Swap (Visa Derivative)
Derivative financial instruments
Notional Amount	82,900	62,039
Derivatives Not Designated as Hedging Instruments | Funding Swap (Visa Derivative) | Included in other liabilities
Derivative financial instruments
Negative fair value, derivative liability	$ 4,233	$ 2,607