Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 22.4	$ (23.1)	$ 122.0	$ (53.2)
Other comprehensive income (loss):
Foreign currency translation adjustments	(2.3)	(4.7)	0.2	(12.3)
Defined benefit pension plans:
Net gain arising during the year	0.0	0.0	1.9	0.0
Unrealized gains (losses) on fixed maturity securities:
(Losses) gains arising during the year	(31.5)	38.2	(60.3)	68.3
Reclassification adjustment for losses (gains) included in net income	8.2	4.5	(11.0)	(15.4)
Other comprehensive income (loss) before tax	(25.6)	38.0	(69.2)	40.6
Income tax provision related to other comprehensive income (loss):
Net gain arising during the year	0.0	0.0	0.4	0.0
(Losses) gains arising during the year	(4.8)	6.5	(11.1)	12.4
Reclassification adjustment for losses (gains) included in net income	0.4	0.5	(1.9)	(0.2)
Income tax (benefit) provision related to other comprehensive income (loss)	(4.4)	7.0	(12.6)	12.2
Other comprehensive income (loss), net of tax	(21.2)	31.0	(56.6)	28.4
Comprehensive income (loss)	$ 1.2	$ 7.9	$ 65.4	$ (24.8)