Supplemental Cash Flow Information (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Significant Noncash Transactions [Line Items]
Non-cash finance lease arrangements	$ 4,424,000
Finance lease		$ 45,979,000
Liabilities assumed			$ 17,613,000
Assets contributed			32,893,000
Capital Lease Obligations
Other Significant Noncash Transactions [Line Items]
Non-cash capital lease arrangements		1,301,000	0
Notes Received from Property Sales
Other Significant Noncash Transactions [Line Items]
Purchased goods and services	$ 3,785,000	$ 2,311,000	$ 27,358,000