Commitments And Contingencies (Annual Minimum Lease Payments) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments And Contingencies [Abstract]
Capital Leases, due on 2018	$ 1,199
Capital Leases, due on 2019	654
Capital Leases, due on 2020	226
Capital Leases, due on 2021	31
Total minimum lease payments	2,110
Less: amount representing interest	(113)
Present value of future payments	1,997
Less: current obligations	(1,147)
Long-term obligations	850
Operating Leases, due on 2018	220,190
Operating Leases, due on 2019	222,489
Operating Leases, due on 2020	224,148
Operating Leases, due on 2021	226,528
Operating Leases, due on 2022	$ 228,093