Summary of Significant Accounting Policies (Accounting Standards Adopted in 2018) (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment on adoption of new accounting standard for revenue recognition		$ 295
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment on adoption of new accounting standard for revenue recognition		$ 295
Retained Earnings | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment on adoption of new accounting standard for revenue recognition	$ 295