Reinsurance (Ceded Reinsurance Receivable Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 688,491	$ 637,859
Reinsurance Recoverables, Percentage of Total	100.00%	100.00%
Other Reinsurers [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 124,320	$ 107,077
Reinsurance Recoverables, Percentage of Total	18.10%	16.80%
AM Best, A+ Rating [Member] | Reinsurer A [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 219,510	$ 199,479
Reinsurance Recoverables, Percentage of Total	31.90%	31.30%
AM Best, A+ Rating [Member] | Reinsurer B [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 191,988	$ 179,522
Reinsurance Recoverables, Percentage of Total	27.90%	28.10%
AM Best, A+ Rating [Member] | Reinsurer C [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 71,542	$ 72,836
Reinsurance Recoverables, Percentage of Total	10.40%	11.40%
AM Best, A++ Rating [Member] | Reinsurer D [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 41,621	$ 41,807
Reinsurance Recoverables, Percentage of Total	6.00%	6.60%
AM Best, A Rating [Member] | Reinsurer E [Member]
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables	$ 39,510	$ 37,138
Reinsurance Recoverables, Percentage of Total	5.70%	5.80%