Derivative Instruments (Gains And Losses On Derivatives Designated As Cash Flow Hedges) (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flow Hedges [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (5,400,000)	$ (1,600,000)	$ 9,700,000
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(11,600,000)	8,300,000	(1,000,000.0)
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	(1,900,000)
Designated as Hedging Instrument [Member] \| Cash Flow Hedges [Member] \| Interest Rate Lock Contracts [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	0	0	0
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	0	1,900,000	200,000
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	0
Designated as Hedging Instrument [Member] \| Cash Flow Hedges [Member] \| Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(5,400,000)	1,600,000	(9,700,000)
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(11,600,000)	6,400,000	(1,200,000)
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	(1,900,000)
Contract Drilling [Member] \| Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(2,000,000.0)	(7,300,000)	400,000
Depreciation Expense [Member] \| Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 13,600,000	$ 900,000	$ 800,000

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
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-Publisher FASB
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-Section 50
-Paragraph 4C
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-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

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- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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