Other Financial Statement Disclosures (Details 2) (USD $) Share data in Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Shareholders' Equit [Abstract]
Other	$ 1,800,000			$ 1,820,000	$ 0
Number of shares representing the cash received in settlement of bankruptcy court claim	52
Accumulated other comprehensive losses (AOCL)		210,096,000		210,096,000					221,082,000
Amortization of pension and postretirement benefit cost		3,701,000	3,426,000	10,986,000	10,203,000
Supplemental Cash Flow Information [Abstract]
Accrued capital expenditures				37,200,000	41,300,000
Interest capitalized in connection with rig construction projects		12,900,000	8,300,000	35,100,000	22,400,000
Income Taxes [Abstract]
U.S. statutory tax rate (in hundredths)				35.00%
U.K. statutory tax rate (in hundredths)						23.00%	24.00%	26.00%
Gain on Sale of Equipment [Abstract]
Gain (loss) on disposals of property and equipment		65,000	559,000	18,979,000	2,678,000
Accumulated Other Comprehensive Income (Loss) [Member]
Shareholders' Equit [Abstract]
Other				0	0
Accumulated other comprehensive losses (AOCL)		210,100,000	215,500,000	210,100,000	215,500,000
Amortization of pension and postretirement benefit cost				10,986,000	10,203,000
Unsecured debt [Member] | Senior Notes due 2017 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		5.00%		5.00%
Maturity of debt				Sep. 01, 2017
Unsecured debt [Member] | Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		7.875%		7.875%
Maturity of debt				Aug. 01, 2019
Unsecured debt [Member] | Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		4.875%		4.875%
Maturity of debt				Jun. 01, 2022
Unsecured debt [Member] | Senior Notes Due 2042 [Member]
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		5.40%		5.40%
Maturity of debt				Dec. 01, 2042
Rowan Companies, Inc. [Member]
Income Taxes [Abstract]
Ownership interest (in hundredths)		100.00%		100.00%
Gain on Sale of Equipment [Abstract]
Gain (loss) on disposals of property and equipment		(2,000)	2,159,000	(231,000)	618,000
Minimum [Member]
Debt Instrument [Line Items]
Number of brokers who provided fair value of debt securities				1
Maximum [Member]
Debt Instrument [Line Items]
Number of brokers who provided fair value of debt securities				2
Rowan Paris [Member]
Gain on Sale of Equipment [Abstract]
Proceeds from sale of rigs	40,000,000
Gain (loss) on disposals of property and equipment	$ 19,200,000