Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Interest		$ 13,843	$ 14,089
Federal income tax		18,500	4,699
Corporate actions related to equity securities, AFS	[1]	4,239	334
Assets acquired under capital lease arrangements		6,933	4,853
AFS Fixed Maturity Securities [Member]
Tax-free exchange of fixed maturity securities		35,425	14,954
Held-to-maturity Securities [Member]
Tax-free exchange of fixed maturity securities		10,045	4,288
National Flood Insurance Program [Member]
Restricted Cash		$ 9,900	$ 8,100

[1] 1Examples of such corporate actions include non-cash acquisitions and stock splits.