Schedule IV - Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated earned premiums [Abstract]
Gross amount	$ 382,300	$ 366,752	$ 372,658
Ceded to other companies	426,946	407,531	423,602
Assumed from other companies	637,054	611,045	591,666
Net amount	$ 592,408	$ 570,266	$ 540,722
Percentage of amount assumed to net	107.50%	107.20%	109.40%