Description of Business and Summary of Significant Accounting Policies (Advertising and Sales Commission) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capitalized Direct Response Advertising Costs [Line Items]
Advertising Expense	$ 6,100	$ 6,200	$ 4,000
Capital Direct Response Advertising, Amortization	3,900	4,100
Capitalized Direct Response Advertising Costs, net	1,900	2,800
Deferred Sales Commission	574	612
Amortization of Deferred Sales Commissions	$ 1,100	$ 1,300
Minimum [Member]
Capitalized Direct Response Advertising Costs [Line Items]
Capitalized Direct Response Advertising Costs, Amortization Period	12 months
Maximum [Member]
Capitalized Direct Response Advertising Costs [Line Items]
Capitalized Direct Response Advertising Costs, Amortization Period	24 months