Derivative Instruments and Hedging Activities - Balance Sheet Disclosures (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024
Derivative [Line Items]
Notional Amount	$ 19,892,076	$ 19,865,937
Other Assets
Derivative [Line Items]
Other Assets	326,722	444,263
Other Liabilities
Derivative [Line Items]
Other Liabilities	332,888	454,200
Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	780,322	780,322
Derivatives designated as hedging instruments: | Interest rate swaps | Other Assets
Derivative [Line Items]
Other Assets	7,078	2,419
Derivatives designated as hedging instruments: | Interest rate swaps | Other Liabilities
Derivative [Line Items]
Other Liabilities	13,641	13,993
Derivatives designated as hedging instruments: | Fair value hedge interest rate swaps | Interest rate swaps
Derivative [Line Items]
Notional Amount	780,322	780,322
Derivatives designated as hedging instruments: | Fair value hedge interest rate swaps | Interest rate swaps | Other Assets
Derivative [Line Items]
Other Assets	7,078	2,419
Derivatives designated as hedging instruments: | Fair value hedge interest rate swaps | Interest rate swaps | Other Liabilities
Derivative [Line Items]
Other Liabilities	13,641	13,993
Derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional Amount	19,111,754	19,085,615
Derivatives not designated as hedging instruments: | Other Assets
Derivative [Line Items]
Other Assets	319,644	441,844
Derivatives not designated as hedging instruments: | Other Liabilities
Derivative [Line Items]
Other Liabilities	319,247	440,207
Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	16,545,194	16,209,499
Derivatives not designated as hedging instruments: | Interest rate swaps | Other Assets
Derivative [Line Items]
Other Assets	304,321	423,683
Derivatives not designated as hedging instruments: | Interest rate swaps | Other Liabilities
Derivative [Line Items]
Other Liabilities	304,084	423,492
Derivatives not designated as hedging instruments: | Foreign currency derivatives
Derivative [Line Items]
Notional Amount	1,532,812	1,688,338
Derivatives not designated as hedging instruments: | Foreign currency derivatives | Other Assets
Derivative [Line Items]
Other Assets	15,295	18,011
Derivatives not designated as hedging instruments: | Foreign currency derivatives | Other Liabilities
Derivative [Line Items]
Other Liabilities	14,968	16,488
Derivatives not designated as hedging instruments: | Mortgage banking derivatives
Derivative [Line Items]
Notional Amount	32,605	45,752
Derivatives not designated as hedging instruments: | Mortgage banking derivatives | Other Assets
Derivative [Line Items]
Other Assets	28	150
Derivatives not designated as hedging instruments: | Mortgage banking derivatives | Other Liabilities
Derivative [Line Items]
Other Liabilities	151	192
Derivatives not designated as hedging instruments: | Credit default swap
Derivative [Line Items]
Notional Amount	1,001,143	1,142,026	$ 1,500,000
Derivatives not designated as hedging instruments: | Credit default swap | Other Assets
Derivative [Line Items]
Other Assets	0	0
Derivatives not designated as hedging instruments: | Credit default swap | Other Liabilities
Derivative [Line Items]
Other Liabilities	44	$ 35
Derivatives not designated as hedging instruments: | Fair value hedge interest rate swaps | Interest rate swaps
Derivative [Line Items]
Notional Amount	$ 10,400