Other Financial Statement Disclosures (Narrative) (Details) (USD $)	0 Months Ended		3 Months Ended		9 Months Ended				9 Months Ended				0 Months Ended			1 Months Ended		0 Months Ended	3 Months Ended
	Jul. 31, 2014	Apr. 25, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jan. 23, 2014	Dec. 31, 2013	Sep. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2014 Minimum [Member] broker	Sep. 30, 2014 Maximum [Member] broker	Jan. 15, 2014 Subsidiary Issuer [Member]	Jan. 15, 2014 Senior Notes due 2024 [Member] Subsidiary Issuer [Member]	Jan. 15, 2014 Senior Notes due 2044 [Member] Subsidiary Issuer [Member]	Feb. 28, 2014 Rowan land rig [Member]	Mar. 31, 2014 Air Transportation Equipment [Member]	Oct. 30, 2014 Subsequent Event [Member]	Sep. 30, 2014 Common Class C [Member]	Sep. 30, 2014 Current Income Tax Receivable [Member]
Debt Instrument [Line Items]
Tax benefits recognized from settlement			$ 46,000,000																	$ 35,000,000
Increase in tax receivable attributable to overpayment of 2014 U.S. federal income taxes			29,000,000
Assets of Discontinued Operations
Net carrying value of disposed rig																24,200,000
Assets of discontinued operations			0		0			23,813,000								4,100,000
Deferred revenues classified as liabilities of discontinued operations																20,100,000
Proceeds from sale of rig																6,000,000
Gain (loss) on disposals of property and equipment																4,000,000
Long-term Debt
Subsidiary ownership percentage by parent													100.00%
Principal amount of offering														400,000,000	400,000,000
Stated interest rate percentage														4.75%	5.85%
Debt instrument, issue amount as percentage of principal														99.898%	99.972%
Proceeds from issuance of debt													792,000,000
Redemption price, percentage of principal amount			100.00%
Borrowing capacity							1,000,000,000.0	750,000,000
Fair Values of Financial Instruments
Number of brokers who provided fair value of debt securities											1	2
Shareholders' Equity
Accumulated other comprehensive losses (AOCL)			135,451,000		135,451,000			142,445,000	135,500,000	210,100,000
Amortization of pension and postemployment benefit cost			2,453,000	3,701,000	7,281,000	10,986,000			7,281,000	10,986,000
Dividends declared (in dollars per share)	$ 0.1	$ 0.1	$ 0.1	$ 0	$ 0.20	$ 0												$ 0.1
Cancellation of shares																			2,000,000,000
Supplemental Cash Flow Information [Abstract]
Accrued capital expenditures					48,900,000	37,200,000
Interest capitalized in connection with rig construction projects			15,500,000	12,900,000	46,000,000	35,100,000
Income Taxes
Effective tax rate			(47.40%)	(0.90%)	(21.10%)	6.70%
Litigation Settlement
Proceeds from litigation settlements					20,900,000
Asset Impairment Charges					8,300,000	0
Property, plant and equipment			$ 7,508,571,000		$ 7,508,571,000			$ 6,385,755,000									$ 12,700,000