Acquisition of Sirius Group - Fair value of net assets acquired and liabilities assumed (Details) - Sirius Group - USD ($) $ in Millions		3 Months Ended
Feb. 26, 2021	Mar. 31, 2021
Business Acquisition [Line Items]
Cash and investments	$ 3,944.1
Insurance and reinsurance balances receivable, net	1,201.0
Reinsurance assets	649.7
Value of business acquired	147.9
Deferred tax asset	228.0
Intangible assets	178.8
Other assets	181.9
Loss and loss adjustment expense reserves	(2,928.5)
Unearned premium reserves	(900.0)
Deferred tax liability	(186.8)
Debt	(728.2)
Other liabilities	(657.7)
Total identifiable net assets acquired	1,130.2
Total purchase price	1,079.8
Bargain purchase gain	$ 50.4	$ 50.4

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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