Reserves for Unpaid Losses and Loss Adjustment Expenses (Activity in the Reserves for Unpaid Losses and Loss Adjustment Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reserves for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Balance at January 1	$ 481,567	$ 450,878	$ 415,135
Less reinsurance recoverable	123,237	102,791	91,943
Net Balance at January 1	358,330	348,087	323,192
Incurred related to:
Claims and Claim Adjustment Expenses Incurred Related to Current Year	248,203	246,080	237,102
Claims and Claim Adjustment Expenses Incurred Related to Prior Years	40,105	7,608	(6,953)
Total incurred	288,308	253,688	230,149
Paid related to:
Current year	92,873	93,067	83,132
Prior years	181,277	150,378	122,122
Total paid	274,150	243,445	205,254
Net Balance at December 31	372,488	358,330	348,087
Plus reinsurance recoverable	154,612	123,237	102,791
Balance at December 31	$ 527,100	$ 481,567	$ 450,878