Bank Call Loans - Additional Information (Narrative) (Details) - USD ($) number in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Bank Call Loans [Abstract]
Broker call rate	0.00%	0.00%
Interest expense on bank call loans	$ 1.4	$ 2.6	$ 1.7