Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (29.6)	$ (25.1)	$ (54.8)	$ 94.9
Other comprehensive income (loss):
Foreign currency translation adjustments	(4.7)	0.0	(12.3)	(0.1)
Unrealized gains (losses) on fixed maturity securities:
Gains (losses) arising during the year	38.2	(7.4)	68.3	91.3
Reclassification adjustment for losses (gains) included in net income	4.5	2.8	(15.4)	7.7
Other comprehensive income before tax	38.0	(4.6)	40.6	98.9
Income tax provision related to other comprehensive income:
Gains (losses) arising during the year	6.5	(0.7)	12.4	15.1
Reclassification adjustment for losses (gains) included in net income	0.5	0.3	(0.2)	1.0
Income tax provision related to other comprehensive income	7.0	(0.4)	12.2	16.1
Other comprehensive income (loss), net of tax	31.0	(4.2)	28.4	82.8
Comprehensive income (loss)	$ 1.4	$ (29.3)	$ (26.4)	$ 177.7