Nature of Operations and Basis of Presentation (Deferred Policy Acquisition Costs) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	$ 164,112
Underwriting costs deferred	112,380
Amortization of deferred policy acquisition costs	(105,227)
Ending unamortized deferred policy acquisition costs	171,265
Impact of unrealized gains and losses on available-for-sale securities	(3,753)	$ (20,220)
Recorded asset at end of period	167,512
Property and Casualty Insurance
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	93,362
Underwriting costs deferred	109,900
Amortization of deferred policy acquisition costs	(101,859)
Ending unamortized deferred policy acquisition costs	101,403
Impact of unrealized gains and losses on available-for-sale securities	0
Recorded asset at end of period	101,403
Life Insurance
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of period	70,750
Underwriting costs deferred	2,480
Amortization of deferred policy acquisition costs	(3,368)
Ending unamortized deferred policy acquisition costs	69,862
Impact of unrealized gains and losses on available-for-sale securities	(3,753)
Recorded asset at end of period	$ 66,109