Schedule II - Condensed Financial Information of Registrant - Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Comprehensive income
Net income available to SiriusPoint	$ (136.3)	$ (44.0)	$ 68.5	$ 169.9	$ 238.4	$ 194.4	$ 58.1	$ 143.5	$ 200.6
Other comprehensive loss
Change in foreign currency translation, net of tax							(0.2)	0.0	0.0
Comprehensive income available to SiriusPoint							57.9	143.5	200.6
Parent Company
Comprehensive income
Net income available to SiriusPoint							58.1	143.5	200.6
Other comprehensive loss
Change in foreign currency translation, net of tax							(0.2)	0.0	0.0
Comprehensive income available to SiriusPoint							$ 57.9	$ 143.5	$ 200.6