INVESTMENTS - Yields at Amortized Cost and Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2025		Dec. 31, 2024
Schedule of Investments [Line Items]
Amortized Cost	$ 29,249.9	[1]	$ 26,374.0	[2]
Fair Value	$ 29,484.8	[1]	$ 26,719.9	[2]
Subordinated loan
Schedule of Investments [Line Items]
Yield on investment, at cost	10.30%		0.00%
Yield on investment, at fair value	10.30%		0.00%
Amortized Cost	$ 530.0		$ 0.0
Fair Value	$ 530.0		$ 0.0
Equity
Schedule of Investments [Line Items]
Yield on investment, at cost	17.20%		16.70%
Yield on investment, at fair value	15.30%		14.80%
Amortized Cost	$ 1,701.0		$ 1,701.0
Fair Value	$ 1,904.0		$ 1,915.0
Subordinated certificates of the SDLP
Schedule of Investments [Line Items]
Yield on investment, at cost	13.20%		12.40%
Yield on investment, at fair value	13.00%		13.20%
Amortized Cost	$ 1,103.0		$ 1,263.0
Fair Value	$ 1,117.0		$ 1,192.0

[1] As of December 31, 2025, the estimated net unrealized gain for federal tax purposes was approximately $300 million based on a tax cost basis of $29.2 billion. As of December 31, 2025, the estimated aggregate gross unrealized gain for federal income tax purposes was approximately $1.3 billion and the estimated aggregate gross unrealized loss for federal income tax purposes was approximately $1.0 billion.

[2] As of December 31, 2024, the estimated net unrealized gain for federal tax purposes was $0.2 billion based on a tax cost basis of $26.5 billion. As of December 31, 2024, the estimated aggregate gross unrealized gain for federal income tax purposes was $1.7 billion and the estimated aggregate gross unrealized loss for federal income tax purposes was $1.5 billion.