Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Amortized cost	$ 16,314.1	$ 16,056.7
Foreign currency, cost	3.0	119.0
Debt financing costs	$ 34.0	$ 38.0
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	281,731,750	284,543,091
Common stock, shares outstanding	281,731,750	284,543,091
Non-controlled/unaffiliated
Amortized cost	$ 12,566.0	$ 12,419.0
Non-controlled/affiliated
Amortized cost	575.0	860.0
Controlled/affiliated
Amortized cost	$ 3,173.0	$ 2,778.0