Equity-Accounted Investments And Other Long-Term Assets (Summary Of Contractual Maturity Of Investment) (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Equity-Accounted Investments And Other Long-Term Assets [Abstract]
Due in one year or less, Cost basis
Due in one year through five years, Cost basis	9,000
Due in five years through ten years, Cost basis
Due after ten years, Cost basis
Total, Cost basis	9,000
Due in one year or less, Estimated fair value
Due in one year through five years, Estimated fair value	9,916
Due in five years through ten years, Estimated fair value
Due after ten years, Estimated fair value
Total, Estimated fair value	$ 9,916