Equity-Accounted Investments And Other Long-Term Assets (Summary Of Contractual Maturity Of Investment) (Details) $ in Thousands	Mar. 31, 2018 USD ($)
Equity-Accounted Investments And Other Long-Term Assets [Abstract]
Due in one year through five years, Cost basis	$ 9,000
Total, Cost basis	9,000
Due in one year through five years, Estimated fair value	9,769
Total, Estimated fair value	$ 9,769