Other Liabilities (Summary Of Other Liabilities Including Pension) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Aug. 29, 2014
Other Liabilities [Abstract]
Lease liability	$ 5,900
Liability for demolition costs	2,623	$ 2,745
Accrued pension	684	684
Security deposit payable	109	114
Finance lease liabilities	51	93
Other	33	17
Other current liabilities	9,400	3,653
Lease make-good provision	6,716	6,667
Accrued pension	4,261	4,469	$ 7,500
Environmental reserve	1,656	1,656
Lease liability		5,900
Acquired leases	32	37
Finance lease liabilities	92	116
Other	978	9
Other liabilities	$ 13,735	$ 18,854