Supplemental Cash Flow Information (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Significant Noncash Transactions [Line Items]
Capital Lease	$ 45,979
Liabilities assumed		$ 17,613
Assets contributed		32,893
Capital Lease Obligations
Other Significant Noncash Transactions [Line Items]
Non-cash capital lease arrangements	1,301	0	$ 55
Notes Received from Property Sales
Other Significant Noncash Transactions [Line Items]
Purchased goods and services	$ 2,311	$ 27,358	$ 2,355