Nature of Business and Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) segment	Jan. 01, 2019 USD ($)
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Number of operating Segments | segment	1
Number of reportable segments | segment	1
Accounting Standards Update 2014-09 [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Cumulative net adjustment to the beginning retained earnings balance	$ 1,950
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Lease assets		$ 80,000
Lease liabilities		$ 90,000