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Property, Plant, and Equipment Narrative (Details) $ in Millions	1 Months Ended						3 Months Ended						6 Months Ended	9 Months Ended		12 Months Ended
	Oct. 31, 2026 USD ($)	Sep. 30, 2026 USD ($)	Jul. 31, 2026 USD ($)	Apr. 30, 2026 USD ($)	Jan. 31, 2026 USD ($)	Apr. 30, 2025 USD ($)	Dec. 31, 2026 USD ($)	Sep. 30, 2026 USD ($)	Jun. 30, 2026 USD ($)	Mar. 31, 2026 USD ($)	Sep. 30, 2025 USD ($) drillship	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2026 USD ($)	Sep. 30, 2025 USD ($) drillship	Dec. 31, 2027 USD ($)	Dec. 31, 2025 USD ($)
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets														$ 102.6	$ 136.3
Semisubmersible Rigs, Retired \| drillship											3				3
Assets held for sale		$ 2.0						$ 2.0						2.0			$ 6.4
Gain (Loss) on Disposition of Property Plant Equipment								27.5			$ 89.5			63.6	$ 117.4
Other Operating Income (Expense), Net								(3.0)	$ 2.8		0.0			(0.2)	(7.8)
Proceeds from (Payment for) Other Financing Activity														1.7	0.0
Angola office
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets											2.7	$ 2.5	$ 5.2
Gain (Loss) on Disposition of Property Plant Equipment											4.0
Floaters \| Operating Segments
Property, Plant, and Equipment [Line Items]
Other Operating Income (Expense), Net														(0.2)	(7.8)
Jackups \| Operating Segments
Property, Plant, and Equipment [Line Items]
Other Operating Income (Expense), Net								0.0						$ 0.0	$ 0.0
V75 \| Jackups Member
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets					$ 5.0						14.0
Gain (Loss) on Disposition of Property Plant Equipment											23.0
V75 \| Jackups Member \| Subsequent Event
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets																$ 5.0
DPS-3, DPS-5 & DPS-6 \| Floaters
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets						$ 10.0
Asset, Impairment Loss											7.8
DPS-1
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets								10.1
DPS-1 \| Floaters
Property, Plant, and Equipment [Line Items]
Asset, Impairment Loss										$ 15.8
Assets held for sale																	$ 6.4
V109 \| Jackups
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets			$ 34.0
V104 \| Jackups Member
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets				$ 40.0
Gain (Loss) on Disposition of Property Plant Equipment								$ 31.3	$ 36.6
V111 \| Jackups
Property, Plant, and Equipment [Line Items]
Proceeds from (Payment for) Other Financing Activity		1.7
V111 \| Jackups \| Subsequent Event
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets	$ 10.5
Gain (Loss) on Disposition of Property Plant Equipment							$ 8.0
PurchaseAndSaleAgreementTerminationPayment	$ 3.0
MS-1 \| Floaters
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets		11.0
Other Operating Income (Expense), Net		$ 3.0
V247 \| Jackups
Property, Plant, and Equipment [Line Items]
Proceeds from disposition of assets											108.0
V247 \| Jackups \| Operating Segments
Property, Plant, and Equipment [Line Items]
Gain (Loss) on Disposition of Other Assets											$ 88.4