Revenue from Contracts with Customers Revenue from Contract with Customers (Schedule of Consumer Brokerage Services) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Consumer Brokerage Services [Line Items]
Consumer brokerage services	$ 3,971	$ 3,726	$ 7,739	$ 7,375
Commission Income [Member]
Consumer Brokerage Services [Line Items]
Consumer brokerage services	2,269	2,193	4,361	4,423
Managed Account Services [Member]
Consumer Brokerage Services [Line Items]
Consumer brokerage services	$ 1,702	$ 1,533	$ 3,378	$ 2,952