Revenue from Contracts with Customers Revenue from Contract with Customers (Schedule of Consumer Brokerage Services) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consumer Brokerage Services [Line Items]
Consumer brokerage services	$ 3,884	$ 3,679	$ 11,623	$ 11,054
Commission Income [Member]
Consumer Brokerage Services [Line Items]
Consumer brokerage services	2,147	2,064	6,508	6,487
Managed Account Services [Member]
Consumer Brokerage Services [Line Items]
Consumer brokerage services	$ 1,737	$ 1,615	$ 5,115	$ 4,567