Significant Accounting Policies (Concentration of Risk) (Details)	12 Months Ended
	Dec. 31, 2017 customer
Direct Written Premium
Concentration Risk [Line Items]
Number of major customers	1
Concentration risk, other risk	0.05
P&C Insurance Operations | Geographic Concentration Risk
Concentration Risk [Line Items]
Number of states in which entity operates	8
P&C Insurance Operations | Sales Revenue, Segment | Product Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	91.00%
P&C Insurance Operations | Sales Revenue, Segment | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	55.00%
Life Insurance Operations | Geographic Concentration Risk
Concentration Risk [Line Items]
Number of states in which entity operates	7
Life Insurance Operations | Sales Revenue, Segment | Product Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	9.00%
Life Insurance Operations | Sales Revenue, Segment | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	79.00%