Reserves for Unpaid Losses and Loss Adjustment Expenses (Activity in the Reserves for Unpaid Losses and Loss Adjustment Expense) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 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	141,909	122,870
Prior years	1,404	4,453
Total incurred	143,313	127,323
Paid related to:
Current year	38,563	28,321
Prior years	107,899	140,339
Total paid	146,462	168,660
Net balance at June 30	302,382	331,151
Plus reinsurance recoverable	249,161	189,401
Balance at June 30	$ 551,543	$ 520,552