Nature of Operations and Basis of Presentation (Deferred Policy Acquisition Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	$ 164,112
Underwriting costs deferred	54,372
Amortization of deferred policy acquisition costs	(52,134)
Ending unamortized deferred policy acquisition costs	166,350
Impact of unrealized gains and losses on available-for-sale securities	(1,277)	$ (11,685)
Recorded asset at end of period	165,073
Property and Casualty Insurance
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	93,362
Underwriting costs deferred	53,084
Amortization of deferred policy acquisition costs	(50,461)
Ending unamortized deferred policy acquisition costs	95,985
Impact of unrealized gains and losses on available-for-sale securities	0
Recorded asset at end of period	95,985
Life Insurance
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	70,750
Underwriting costs deferred	1,288
Amortization of deferred policy acquisition costs	(1,673)
Ending unamortized deferred policy acquisition costs	70,365
Impact of unrealized gains and losses on available-for-sale securities	(1,277)
Recorded asset at end of period	$ 69,088