Schedule VI - Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Information Concerning Property and Casualty Insurance Operations
Current Year	$ 538,881	$ 642,882	$ 513,734
Prior Years	(45,448)	(30,313)	(37,368)
Consolidated Property & Casualty Subsidiaries
Supplemental Information Concerning Property and Casualty Insurance Operations
Deferred Policy Acquisition Costs	70,996	68,937	67,329
Reserves for Unpaid Claims and Claims Adjustment Expenses	560,321	553,977	482,012
Unearned Premiums	418,033	401,961	390,361
Earned Premiums	755,760	738,164	716,875
Net Investment Income	38,413	40,534	42,303
Current Year	538,881	642,882	513,734
Prior Years	(45,448)	(30,313)	(37,368)
Amortization of Deferred Policy Acquisition Costs	141,540	138,239	132,526
Paid Claims and Claims Adjustment Expenses	502,552	547,620	450,267
Premiums Written	$ 766,470	$ 746,180	$ 734,914