Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Gross Notional	$ 358,596,065	$ 266,639,029
Fair Value Assets	15,332,694	9,045,737
Fair Value Liabilities	(27,242,213)	(21,248,026)
Derivatives Designated as Hedge Accounting Instruments:
Derivative [Line Items]
Gross Notional	3,311,693	2,277,700
Fair Value Assets	202,606	121,243
Fair Value Liabilities	(27,732)	(54,282)
Derivatives Designated as Hedge Accounting Instruments: \| Interest Rate Swaps
Derivative [Line Items]
Gross Notional	2,851	3,064
Fair Value Assets	0	0
Fair Value Liabilities	(209)	(238)
Derivatives Designated as Hedge Accounting Instruments: \| Foreign Currency Swaps
Derivative [Line Items]
Gross Notional	3,308,842	2,274,636
Fair Value Assets	202,606	121,243
Fair Value Liabilities	(27,523)	(54,044)
Derivatives Not Qualifying as Hedge Accounting Instruments:
Derivative [Line Items]
Gross Notional	355,284,372	264,361,329
Fair Value Assets	15,130,088	8,924,494
Fair Value Liabilities	(27,214,481)	(21,193,744)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Interest Rate Swaps
Derivative [Line Items]
Gross Notional	174,170,160	163,179,764
Fair Value Assets	9,029,399	6,605,817
Fair Value Liabilities	(20,888,553)	(17,820,436)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Interest Rate Future
Derivative [Line Items]
Gross Notional	1,518,400	1,332,600
Fair Value Assets	1,967	3,055
Fair Value Liabilities	(1,443)	(210)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Interest Rate Option
Derivative [Line Items]
Gross Notional	29,135,000	29,738,000
Fair Value Assets	279,414	189,112
Fair Value Liabilities	(1,406,265)	(969,718)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| interest rate forward
Derivative [Line Items]
Gross Notional	0	1,458,000
Fair Value Assets	0	741
Fair Value Liabilities	0	(3,196)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Interest Rate Total Return Swaps
Derivative [Line Items]
Gross Notional	223,721	0
Fair Value Assets	1,472	0
Fair Value Liabilities	(2,121)	0
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Foreign Currency Forwards
Derivative [Line Items]
Gross Notional	1,146,861	744,576
Fair Value Assets	30,078	1,772
Fair Value Liabilities	(181)	(12,232)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Credit Default Swaps
Derivative [Line Items]
Gross Notional	911,850	643,280
Fair Value Assets	9,606	7,727
Fair Value Liabilities	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Foreign Currency Swaps
Derivative [Line Items]
Gross Notional	2,285,052	2,237,331
Fair Value Assets	164,152	96,618
Fair Value Liabilities	(9,277)	(31,294)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Equity Total Return Swap
Derivative [Line Items]
Gross Notional	23,025,217	15,049,993
Fair Value Assets	1,160,080	418,084
Fair Value Liabilities	(1,182,913)	(803,452)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Equity Options
Derivative [Line Items]
Gross Notional	117,107,059	49,247,510
Fair Value Assets	4,453,762	1,600,335
Fair Value Liabilities	(3,717,637)	(1,552,706)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Equity Futures
Derivative [Line Items]
Gross Notional	1,802,205	418,973
Fair Value Assets	15	1,232
Fair Value Liabilities	(6,060)	(500)
Derivatives Not Qualifying as Hedge Accounting Instruments: \| Synthetic Gics
Derivative [Line Items]
Gross Notional	3,958,847	311,302
Fair Value Assets	143	1
Fair Value Liabilities	$ (31)	$ 0

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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