Reserves for Unpaid Losses and Loss Adjustment Expenses (Activity in the Reserves for Unpaid Losses and Loss Adjustment Expense) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Reserves for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Balance at January 1	$ 481,567	$ 450,878
Less reinsurance recoverable	123,237	102,791
Net balance at January 1	358,330	348,087
Incurred related to:
Current year	184,685	177,017
Prior years	20,240	(783)
Total incurred	204,925	176,234
Paid related to:
Current year	61,288	65,339
Prior years	128,329	116,488
Total paid	189,617	181,827
Net balance at September 30	373,638	342,494
Plus reinsurance recoverable	157,861	112,506
Balance at September 30	$ 531,499	$ 455,000