Leases (Schedule of Operating lease right-of-use assets and lease obligations) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases
Right of use asset	$ 90,280	$ 75,176
Right of use asset included in balance sheet	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Current lease liability	$ 17,702	$ 17,532
Current lease liability included in balance sheet	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Non current lease liability	$ 72,614	$ 57,897
Non current lease liability included in balance sheet	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Lease liability	$ 90,316	$ 75,429