Commitments And Contingencies And Other Matters - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies [Line Items]
Total investment	$ 2,922,274	$ 2,785,778
Q7000
Commitments And Contingencies [Line Items]
Total investment	$ 536,400
Q7000 | Contract Signing
Commitments And Contingencies [Line Items]
Percentage of contract price	20.00%
Q7000 | Due 2016
Commitments And Contingencies [Line Items]
Percentage of contract price	20.00%
Q7000 | Due 2017
Commitments And Contingencies [Line Items]
Percentage of contract price	20.00%
Q7000 | Due 2018
Commitments And Contingencies [Line Items]
Percentage of contract price	20.00%
Q7000 | Vessel Delivery
Commitments And Contingencies [Line Items]
Percentage of contract price	20.00%
Siem | Siem Helix 1 and Siem Helix 2
Commitments And Contingencies [Line Items]
Term of charter agreement	7 years
Shipyard | Q7000
Commitments And Contingencies [Line Items]
Total investment	$ 346,000