Derivative Instruments - Derivatives Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest Rate Fair Value Hedges
Carrying amount of the hedged liability - Subordinated bank note - 2025	$ 151,454				$ 144,296				$ 151,454	$ 144,296
Statement of income line where the gain (loss) on the fair value hedge was recorded:
Interest expense on borrowings									72,072	43,144	$ 27,807
Other noninterest income	158,052	$ 94,258	$ 109,718	$ 103,504	123,868	$ 112,064	$ 110,151	$ 108,314	465,532	454,397	436,063
Summary of Net Investment Hedge Activity [Abstract]
Effect of net investment hedges on accumulated other comprehensive income									(7,001)	13,762
Fair Value Hedging [Member]
Statement of income line where the gain (loss) on the fair value hedge was recorded:
Interest expense on borrowings											0
Not Designated as Hedges | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Termination Derivative	1,100,000								1,100,000
Derivatives designated as hedges | Other noninterest income
Statement of income line where the gain (loss) on the fair value hedge was recorded:
Other noninterest income									0	0	23,969
Derivatives designated as hedges | Interest expense - borrowings
Statement of income line where the gain (loss) on the fair value hedge was recorded:
Gain (loss) of fair value hedge: Hedged item									(6,937)	2,163	808
Gain (loss) of fair value hedge: Derivative designated as a hedging instrument									(6,986)	2,275	609
Net income (expense) recognized on fair value hedge in interest expense on borrowings									49	(112)	199
Derivatives designated as hedges | Net investment hedges | Forward foreign exchange contracts
Summary of Net Investment Hedge Activity [Abstract]
Effect of net investment hedges on accumulated other comprehensive income									(7,001)	13,762	$ (4,430)
Subordinated bank notes
Interest Rate Fair Value Hedges
Hedge related adjustment	$ 2,773				$ (4,165)				$ 2,773	$ (4,165)