SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue and Expense Recognition [Abstract}
Revenues received but unearned	$ 78,800,000	$ 58,400,000
Deferred drilling costs	41,500,000	33,000,000
Cash Equivalents [Abstract]
Maximum maturity period for highly liquid cash investments to be considered cash equivalent	3 months
Accounts Receivable and Allowance for Doubtful Accounts [Abstract]
Allowance for doubtful accounts	0	300,000
Accrued income tax refund	88,600,000
Unreimbursed costs related to the salvage of lost or damaged rigs	1,900,000	4,600,000
Property and Depreciation [Abstract]
Interest incurred and capitalized during construction	33,400,000	54,500,000	40,000,000
Repairs and maintenance expense, continuing operations	132,200,000	97,600,000	70,300,000
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset impairment charges	5,200,000	8,000,000
Recognized an additional impairment charge for the rig	3,900,000
Carrying amount of assets impaired	22,954,000	27,661,000
Foreign Currency Transactions [Abstract]
Foreign currency transaction gains (losses)	500,000	800,000	400,000
Income Taxes [Abstract]
U.S. Statutory income tax rate (in hundredths)	35.00%
Shares for basic and diluted income per share [Abstract]
Average common shares outstanding (in thousands of shares)	122,998	125,044	117,021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average shares for diluted computations (in thousands of shares)	123,872	126,393	118,818
Excluding antidilutive securities
Total potentially dilutive shares excluded from computation due to antidilutive for current disclosure (in thousands of shares)	658	308	153
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average shares for diluted computations (in thousands of shares)	457	765	1,270
Employee and director stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average shares for diluted computations (in thousands of shares)	160	298	417
Excluding antidilutive securities
Total potentially dilutive shares excluded from computation due to antidilutive for current disclosure (in thousands of shares)	42	42	153
Stock appreciation rights and other [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Average shares for diluted computations (in thousands of shares)	257	286	110
Excluding antidilutive securities
Total potentially dilutive shares excluded from computation due to antidilutive for current disclosure (in thousands of shares)	616	266	0
Rowan Juneau [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Carrying amount of assets impaired	18,700,000
Le Tourneau [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Carrying amount of assets impaired	$ 26,900,000
Jack-up drilling rigs: Hulls [Member]
Estimated useful lives and salvage value [Abstract]
Maximum useful life (in years)	35
Salvage value	20.00%
Jack-up drilling rigs: Legs [Member]
Estimated useful lives and salvage value [Abstract]
Maximum useful life (in years)	30
Salvage value	20.00%
Jack-up drilling rigs: Quarters [Member]
Estimated useful lives and salvage value [Abstract]
Maximum useful life (in years)	25
Salvage value	20.00%
Jack-up drilling rigs: Drilling equipment [Member]
Estimated useful lives and salvage value [Abstract]
Minimum useful life (in years)	10
Maximum useful life (in years)	25
Salvage value	20.00%
Drill pipe and tubular equipment [Member]
Estimated useful lives and salvage value [Abstract]
Maximum useful life (in years)	4
Salvage value	10.00%
Other property and equipment [Member]
Estimated useful lives and salvage value [Abstract]
Minimum useful life (in years)	3
Maximum useful life (in years)	30