Goodwill and intangible assets - Components of goodwill and intangible assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite lived intangible Asset
Accumulated Amortization	$ (26.0)	$ (10.2)
Net Balance	173.5	189.3
Goodwill
Gross Balance	400.7	400.7
Foreign currency translation	(0.1)	0.3
Net Balance	400.6	401.0
Indefinite lived intangible assets
Gross Balance	22.1	27.0	$ 5.0
Impairments	(8.0)	(5.0)
Gross carrying amount of intangible assets	635.3	632.2
Impairment of intangible assets	(13.0)	(5.0)
Foreign currency translation including goodwill	(0.1)	0.3
Net carrying amount of intangible assets	596.2	617.3	$ 5.0
Trade Names
Indefinite lived intangible assets
Gross Balance	27.0	27.0
Impairments	(13.0)	(5.0)
Net Balance	14.0	22.0
Insurance licenses
Indefinite lived intangible assets
Gross Balance	8.1	5.0
Net Balance	8.1	5.0
Customer relationships
Finite lived intangible Asset
Gross Balance	17.0	17.0
Accumulated Amortization	(2.2)	(0.8)
Net Balance	14.8	16.2
Distribution relationships
Finite lived intangible Asset
Gross Balance	151.0	151.0
Accumulated Amortization	(15.8)	(6.2)
Net Balance	135.2	144.8
Trade Names
Finite lived intangible Asset
Gross Balance	16.0	16.0
Accumulated Amortization	(3.7)	(1.6)
Net Balance	12.3	14.4
Technology
Finite lived intangible Asset
Gross Balance	15.5	15.5
Accumulated Amortization	(4.3)	(1.6)
Net Balance	$ 11.2	$ 13.9