Derivative Instruments and Hedging Activities - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($) swap	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) swap	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)
Derivative [Line Items]
Notional amount	$ 20,625,667		$ 20,625,667		$ 19,865,937
Loans	49,391,420		49,391,420		48,799,711
Consumer loans
Derivative [Line Items]
Loans	3,985,493		3,985,493		3,590,837
Consumer loans | Automobile
Derivative [Line Items]
Loans	2,178,841		2,178,841		1,901,065
Derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	19,845,345		19,845,345		19,085,615
Interest rate swaps
Derivative [Line Items]
Accumulated net after-tax gains related to effective cash flow hedges	806		806		1,200
Amounts reclassified to income statement	875		875
Interest rate swaps | Fair value hedge interest rate swaps | Interest income
Derivative [Line Items]
Fee income related to derivative interest rate swaps executed with commercial loan customers	0	$ 676	0	$ 5,555
Interest rate swaps | Fair value hedge interest rate swaps | Noninterest Income
Derivative [Line Items]
Fee income related to derivative interest rate swaps executed with commercial loan customers	8,300	6,800	14,000	11,300
Interest rate swaps | Derivatives designated as hedging instruments
Derivative [Line Items]
Derivative, notional amount, terminated						$ 500,000
Notional amount	780,322		780,322		780,322
Interest rate swaps | Derivatives designated as hedging instruments | Fair value hedge interest rate swaps
Derivative [Line Items]
Notional amount	$ 780,322		$ 780,322		780,322
Interest rate swaps | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Number of instruments held | swap	63		63
Notional amount	$ 16,982,940		$ 16,982,940		16,209,499
Interest rate swaps | Derivatives not designated as hedging instruments: | Fair value hedge interest rate swaps
Derivative [Line Items]
Number of instruments held | swap	2		2
Notional amount	$ 10,400		$ 10,400
Interest rate swaps | Derivatives not designated as hedging instruments: | Risk Participation Agreement
Derivative [Line Items]
Notional amount	946,900		946,900
Credit default swap | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	874,898	$ 1,500,000	874,898	$ 1,500,000	$ 1,142,026
Derivative, cost of hedge	$ 1,800		$ 3,800