Income Taxes - Valuation allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Valuation allowance beginning of the year	$ 6.6	$ 7.1	$ 6.6
Increases recorded as an expense to income tax provision	7.2		0.5
Decreases recorded for valuation allowance release		(0.5)
Valuation allowance end of the year	$ 13.8	$ 6.6	$ 7.1