Related Party Transactions (Management) (Narrative) (Details) - Management - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Equipment, Supplies and Services
Related Party Transaction [Line Items]
Payments, related party	$ 30,700,000	$ 16,200,000	$ 51,100,000	$ 41,500,000
Payables, related party	500,000		500,000		$ 8,900,000
Revenue, related party	900,000	1,300,000	2,100,000	2,300,000
Receivables, net, related party	400,000		400,000		500,000
Subcontracting Arrangements
Related Party Transaction [Line Items]
Payments, related party	16,800,000	$ 0	45,800,000	$ 600,000
Payables, related party	$ 14,900,000		$ 14,900,000		$ 1,400,000

Amount for accounts payable to related parties.

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