Business and Summary of Significant Accounting Principles (Recently Issued and Recently Adopted Accounting Pronouncements) (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ (236,594)	$ (257,544)
Cumulative effect of ASU 2016-09 adoption			7,095
Retained Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of ASU 2016-09 adoption			$ 7,077
ASU 2014-09 | Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 33,300