Loss and Loss Adjustment Expense Reserves (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross beginning balance	$ 999.6	$ 751.9	$ 894.7	$ 696.0
Less: beginning reinsurance recoverable on unpaid losses	(396.0)	(447.5)	(428.9)	(433.4)
Net loss and LAE reserves	603.6	304.4	465.8	262.6
Loss and LAE incurred relating to:
Current year losses	143.2	61.6	268.9	127.1
Prior year losses	(22.7)	(9.0)	(26.4)	(8.5)
Net incurred losses and LAE	120.5	52.6	242.5	118.6
Loss and LAE paid relating to:
Current year losses	(14.1)	(1.1)	(14.7)	(2.5)
Prior year losses	(54.4)	(18.3)	(93.8)	(41.8)
Net paid loss and LAE	(68.5)	(19.4)	(108.5)	(44.3)
Change in TPC providers’ participation	0.0	0.0	57.5	(2.2)
Foreign currency translation and other adjustments to loss and LAE reserves	(9.0)	(2.9)	(10.7)	0.0
Net ending balance	646.6	334.7	646.6	334.7
Plus: ending reinsurance recoverable on unpaid losses	375.5	425.3	375.5	425.3
Gross ending balance	1,022.1	760.0	1,022.1	760.0
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and loss adjustment expense reserves	375.5	425.3	375.5	425.3	$ 428.9	$ 433.4
Ark
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross beginning balance			894.7
Loss and LAE paid relating to:
Gross ending balance	1,022.1		1,022.1
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance recoverables	398.7	431.3	398.7	431.3	448.4
TPC Providers | Ark
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance recoverables	182.4		182.4
TPC Providers
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: beginning reinsurance recoverable on unpaid losses	$ (207.3)	(331.0)	$ (276.8)	(319.2)
Loss and LAE paid relating to:
Plus: ending reinsurance recoverable on unpaid losses		314.6		314.6
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss and loss adjustment expense reserves		314.6		314.6	$ 276.8	$ 319.2
Reinsurance recoverables		$ 314.6		$ 314.6
Ark | TPC Providers
Liability for Claims and Claims Adjustment Expense [Line Items]
Percent of underwriting capital provided by third parties						42.80%	58.30%	57.60%