Reinsurance (Cumulative Paid Claims) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	$ 136.0
Incident Year 2015 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	33.4	$ 33.4	$ 33.4	$ 33.4	$ 31.9
Incident Year 2016 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	26.0	26.0	26.0	$ 24.7
Incident Year 2017 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	22.6	22.5	$ 21.3
Incident Year 2018 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	25.7	$ 24.2
Incident Year 2019 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	$ 28.3