CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2025		Dec. 31, 2024
Statement of Financial Position [Abstract]
Amortized cost of investments	$ 29,249.9	[1]	$ 26,374.0	[2]
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001
Common stock, shares authorized (in shares)	1,000		1,000
Common stock, shares issued (in shares)	718		672
Common stock, shares outstanding (in shares)	718		672

[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.