Leased Assets and Liabilities (Operating and Finance Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating	$ 201,916	$ 200,752
Finance	$ 23,973	10,443
Finance	us-gaap:AssetsAbstract
Total leased assets	$ 225,889	211,195
Liabilities
Current operating lease liabilities	39,182	36,060
Noncurrent operating lease liabilities	180,292	177,711
Accounts payable and accrued liabilities	$ 4,714	2,879
Accounts payable and accrued liabilities	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Other noncurrent liabilities	$ 18,862	7,927
Other noncurrent liabilities	us-gaap:OtherLiabilitiesNoncurrent
Total lease liabilities	$ 243,050	$ 224,577
Maximum
Lessee, Lease, Description [Line Items]
Term of contract	15 years
Option to extend	5 years