Reserves for Unpaid Losses and Loss Adjustment Expenses (Activity in the Reserves for Unpaid Losses and Loss Adjustment Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reserves for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Balance at January 1	$ 527,247	$ 527,100
Less reinsurance recoverable	221,716	154,612
Net balance at January 1	305,531	372,488
Incurred related to:
Current year	70,153	64,205
Prior years	(66)	(530)
Total incurred	70,087	63,675
Paid related to:
Current year	12,633	13,829
Prior years	60,581	72,432
Total paid	73,214	86,261
Net balance at March 31	302,404	349,902
Plus reinsurance recoverable	227,822	179,782
Balance at March 31	$ 530,226	$ 529,684