Consolidated Statements of (Loss) Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Net earned insurance and reinsurance premiums	$ 372.6	$ 374.2	$ 1,177.1	$ 1,056.8
Net investment income	1.7	22.8	30.0	67.3
Net realized investment (losses) gains	(3.8)	15.3	23.6	39.9
Net unrealized investment gains (losses)	31.2	53.9	(3.9)	143.4
Net foreign exchange (losses) gains	(21.3)	4.9	(18.9)	9.4
Other revenue	15.8	16.3	30.3	51.3
Total revenues	396.2	487.4	1,238.2	1,368.1
Expenses
Loss and loss adjustment expenses	305.4	348.6	972.8	810.5
Insurance and reinsurance acquisition expenses	83.6	75.1	236.4	215.4
Other underwriting expenses	41.3	35.4	115.6	106.2
General and administrative expenses	34.4	28.0	90.4	80.6
Intangible asset amortization expenses	3.9	3.9	11.8	11.8
Interest expense on debt	8.1	7.7	23.8	23.3
Total expenses	476.7	498.7	1,450.8	1,247.8
Pre-tax income (loss)	(80.5)	(11.3)	(212.6)	120.3
Income tax (expense) benefit	(23.5)	3.7	(19.9)	(15.6)
Net (loss) income	(104.0)	(7.6)	(232.5)	104.7
Loss (income) attributable to non-controlling interests	(0.2)	(0.4)	(0.2)	(1.6)
(Loss) income attributable to Sirius Group	(104.2)	(8.0)	(232.7)	103.1
Change in carrying value of Series B preference shares	8.7	5.3	25.5	(3.9)
Net (loss) income attributable to Sirius Group's common shareholders	$ (95.5)	$ (2.7)	$ (207.2)	$ 99.2
Net (loss) income per common share and common share equivalent
Basic earnings per common share and common share equivalent (in dollars per share)	$ (0.83)	$ (0.02)	$ (1.80)	$ 0.78
Diluted earnings per common share and common share equivalent (in dollars per share)	$ (0.83)	$ (0.06)	$ (1.83)	$ 0.78
Weighted average number of common shares and common share equivalents outstanding:
Basic weighted average number of common shares and common share equivalents outstanding (in shares)	115,297,945	115,251,853	115,279,197	115,225,942
Diluted weighted average number of common shares and common share equivalents outstanding (in shares)	115,297,945	127,153,523	127,180,867	115,619,222