Quarterly report pursuant to Section 13 or 15(d)

Revenue Recognition (Schedule Of Contract Liabilities From Contract With Customers) (Details)

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Revenue Recognition (Schedule Of Contract Liabilities From Contract With Customers) (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2018
USD ($)
Organization, Consolidation, And Basis Of Presentation [Abstract]  
Contract liabilities at beginning of period $ 14,417
Increase due to deferral of revenue 14,357
Decreases due to recognition of revenue (13,059)
Contract liabilities at end of period $ 15,715