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Contingencies (Narrative) (Details) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended		24 Months Ended
Contingencies (Narrative) (Details) $ in Millions	Aug. 31, 2026 USD ($)	Nov. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) jackup	Sep. 30, 2025	Sep. 30, 2026 USD ($) jackup	Sep. 30, 2025	Dec. 31, 2024 jackup	May 31, 2026	Dec. 31, 2025 USD ($)	Apr. 03, 2023 USD ($)	Jan. 31, 2020 jackup
Loss Contingencies [Line Items]
Number of Newbuild Jackup Rigs \| jackup			20		20
Maximum Contingent Contributions To Joint Venture			$ 1,250.0		$ 1,250.0
Max. amount by which VAL commitment to ARO will be reduced with each rig delivery			250.0		250.0
Letters of credit outstanding, amount			113.7		113.7
Deposit Liabilities, Collateral Issued, Financial Instruments			14.8		14.8				$ 16.3
Reduced Contingent Contributions To Joint Venture			$ 1,100.0		$ 1,100.0
Number of ARO newbuild rigs ordered \| jackup											2
Number Of Newbuild Jackup Rigs Delivered \| jackup							2
Effective Income Tax Rate, Continuing Operations, Excluding Discrete Items			20.10%	14.10%	21.10%	14.80%
DownPaymentMadeForARONewbuild5	$ 45.0
Kingdom3 & 4
Loss Contingencies [Line Items]
Percentage of Down Payment Paid for ARO Newbuilds								25.00%
Long-Term Purchase Commitment, Amount		$ 300.0
Kingdom 5 & 6
Loss Contingencies [Line Items]
Percentage of Down Payment Paid for ARO Newbuilds	25.00%
Long-Term Purchase Commitment, Amount	$ 360.0
Kingdom 5
Loss Contingencies [Line Items]
Percentage of Down Payment Paid for ARO Newbuilds	50.00%
Long-Term Purchase Commitment, Amount	$ 45.0
Kingdom 6
Loss Contingencies [Line Items]
Long-Term Purchase Commitment, Amount	$ 90.0
Revolving Credit Facility
Loss Contingencies [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity										$ 375.0