Lease Obligations (Schedule Of Future Minimum Lease Payments For Capitalized And Non-Cancelable Operating Leases) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Lease Obligations [Abstract]
Capitalized Leases, 2018	$ 1,373
Capitalized Leases, 2019	1,143
Capitalized Leases, 2020	1,050
Capitalized Leases, 2021	738
Capitalized Leases, 2022	752
Capitalized Leases, Later years	6,739
Capitalized Leases, Total minimum lease payments	11,795
Capitalized Leases, Less: amounts representing imputed interest	(4,073)
Capitalized Leases, Present value of minimum lease payments	7,722
Capitalized Leases, Less current portion of capitalized lease obligations	(644)
Capitalized Leases, Capitalized lease obligations, excluding current portion	7,078
Operating Leases, 2018	15,930
Operating Leases, 2019	12,273
Operating Leases, 2020	7,495
Operating Leases, 2021	5,875
Operating Leases, 2022	5,097
Operating Leases, Later years	9,738
Operating Leases, Total minimum lease payments	$ 56,408