Description of Business and Summary of Significant Accounting Policies Capitalized Contract Costs (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Deferred Contract Costs [Roll Forward]
Capitalized Contract Cost, Net, beginning of period	$ 0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Capitalized Contract Costs	2,401
Capitalized Contract Cost, Amortization	(469)
Capitalized Contract Costs, net additions	228
Capitalized Contract Cost, Net, end of period	$ 2,160