Reinsurance (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Allowance for Reinsurance Recoverable
Valuation allowance recorded against reinsurance recoverable	$ 4.2	$ 1.6
Reinsurance Recoverable | Largest reinsurance recoverable, Customer One
Concentration risk percentage	27.10%	21.50%
Reinsurance Recoverable | Largest reinsurance recoverable, Customer Two
Concentration risk percentage	19.90%	13.80%
Reinsurance Recoverable | Largest reinsurance recoverable, Customer Three
Concentration risk percentage	7.70%	13.10%
Allowance for Reinsurance Recoverable | Largest reinsurance recoverable, Customer One
Concentration risk percentage	27.10%	22.70%
Allowance for Reinsurance Recoverable | Largest reinsurance recoverable, Customer Two
Concentration risk percentage	17.90%	8.30%
Allowance for Reinsurance Recoverable | Largest reinsurance recoverable, Customer Three
Concentration risk percentage	5.60%	3.20%