Reserves For Claims Summary Of The Company's Loss Reserves (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Known title claims	$ 3,704	$ 4,646
IBNR	29,066	30,155
Total loss reserves	$ 32,770	$ 34,801	$ 35,305
% of known title reserves	11.30%	13.40%
% of IBNR	88.70%	86.60%
% of total loss reserves	100.00%	100.00%