Supplemental Financial Statement Information (Allowance for Credit on Losses for Accounts and Other Reveivables) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts	$ 13,959		$ 18,899
Allowance for credit losses	4,988	$ 27,941
Accounts and other receivables	13,959	32,474
Other assets	16,788	0
ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts	35,344	17,830	$ 30,747	$ 32,474
Allowance for credit losses	2,488	12,692
Write-offs, recoveries and other	(7,085)	(13,384)
ASU 2016-13 | Cumulative Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts	$ 0	$ 15,336