Investments - Schedule of Net Investment Earnings (Loss) from NGP (Details) - NGP Management Company LLC - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Management fee related revenues from NGP Management	$ 78.6	$ 71.0	$ 72.9
Expenses related to the investment in NGP Management	(13.8)	(11.5)	(10.8)
Amortization of basis differences from the investment in NGP Management	0.0	(1.4)	(2.9)
Net investment income from NGP Management	$ 64.8	$ 58.1	$ 59.2