Reinsurance and Policy Benefits and Losses, Claims, and Loss Expenses Payable (Activity in the Liability for Unpaid Losses and Loss Adjustment Expenses for Property and Casualty Insurance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Paid related to:
Net balance at December 31	$ 139,064
Plus: reinsurance recoverables	94,490
Balance at December 31	233,554
Operating Segments [Member] | Property and Casualty Insurance [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance at January 1	244,400	$ 251,964	$ 271,609
Less: reinsurance recoverables	103,952	107,311	120,894
Net balance at January 1	140,448	144,653	150,715
Incurred related to:
Current year	15,749	13,297	11,713
Prior years	233	107	585
Total incurred	15,982	13,404	12,298
Paid related to:
Current year	8,969	7,777	7,007
Prior years	8,397	9,832	11,353
Total paid	17,366	17,609	18,360
Net balance at December 31	139,064	140,448	144,653
Plus: reinsurance recoverables	94,490	103,952	107,311
Balance at December 31	$ 233,554	$ 244,400	$ 251,964