Reinsurance - Effect of Reinsurance Premiums (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effect of reinsurance on premiums earned and benefits incurred
Direct earned premiums	$ 26.9	$ 24.8	$ 26.4
Premiums assumed	0.3	2.6	5.3
Premiums ceded	(26.2)	(22.9)	(10.0)
Net earned premiums	1.0	4.5	21.7
Direct policyholder benefits	37.8	101.1	31.4
Policyholder benefits assumed	0.0	2.0	6.0
Policyholder benefits ceded	(37.4)	(100.1)	(21.1)
Net policyholder benefits	0.4	3.0	16.3
Long Duration
Effect of reinsurance on premiums earned and benefits incurred
Direct earned premiums	8.4	9.4	9.1
Premiums assumed	0.0	0.0	0.0
Premiums ceded	(8.4)	(9.4)	(9.1)
Net earned premiums	0.0	0.0	0.0
Direct policyholder benefits	27.0	92.1	20.4
Policyholder benefits assumed	0.0	0.2	0.0
Policyholder benefits ceded	(27.0)	(92.3)	(20.4)
Net policyholder benefits	0.0	0.0	0.0
Short Duration
Effect of reinsurance on premiums earned and benefits incurred
Direct earned premiums	18.5	15.4	17.3
Premiums assumed	0.3	2.6	5.3
Premiums ceded	(17.8)	(13.5)	(0.9)
Net earned premiums	1.0	4.5	21.7
Direct policyholder benefits	10.8	9.0	11.0
Policyholder benefits assumed	0.0	1.8	6.0
Policyholder benefits ceded	(10.4)	(7.8)	(0.7)
Net policyholder benefits	$ 0.4	$ 3.0	$ 16.3

Amount of earned premiums assumed from other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
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Amount of earned premiums ceded to other entities.

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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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