Description of Business and Summary of Significant Accounting Policies Advertising Costs (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Advertising Costs [Abstract]
Advertising Expense	$ 3,900	$ 3,100
Capitalized Direct Response Advertising Costs [Line Items]
Capital Direct Response Advertising, Amortization		$ 2,000
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
ASC 340-40 [Member]
Capitalized Direct Response Advertising Costs [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(497)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (1,932)