Reinsurance (Cumulative Paid Claims) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	$ 140.0
Incident Year 2016 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	26.0	$ 26.0	$ 26.0	$ 26.0	$ 24.7
Incident Year 2017 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	22.6	22.6	22.5	$ 21.3
Incident Year 2018 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	25.8	25.7	$ 24.2
Incident Year 2019 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	30.2	$ 28.3
Incident Year 2020 [Member]
Cumulative Paid Claims [Line Items]
Cumulative Paid Claims	$ 35.4