Pension And Other Liabilities (Summary Of Other Liabilities Including Pension) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Aug. 29, 2014
Other Liabilities [Abstract]
Liability for demolition costs		$ 2,783
Accrued pension	$ 684	684
Security deposit payable	68	69
Finance lease liabilities	28	40
Other	33	43
Other current liabilities	813	3,619
Lease make-good provision	6,131	7,766	$ 7,408
Accrued pension	3,138	3,605		$ 7,500
Deferred rent liability	2,484	3,930
Environmental reserve	1,656	1,656
Lease liability	5,900	5,900
Acquired leases	11	21
Finance lease liabilities		28
Other non-current liabilities	$ 19,320	$ 22,906