Income Taxes - Additional Information (Detail)	3 Months Ended	12 Months Ended								12 Months Ended		12 Months Ended				3 Months Ended
	Mar. 31, 2013 USD ($)	Dec. 31, 2011 USD ($) Drillship	Dec. 31, 2012 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2012 Other Assets [Member] USD ($)	Dec. 31, 2011 Other Assets [Member] USD ($)	Dec. 31, 2012 Other Liabilities [Member] USD ($)	Dec. 31, 2011 Other Liabilities [Member] USD ($)	Dec. 31, 2009 2004 & 2005 Tax Year [Member] Brazil [Member] USD ($)	Dec. 31, 2012 2000 Tax Year [Member] Brazil [Member] USD ($)	Dec. 31, 2011 2006 Tax Year [Member] Brazil [Member] USD ($)	Jan. 31, 2012 2006 Tax Year [Member] Mexico [Member] USD ($)	Feb. 28, 2012 2007 Tax Year [Member] Brazil [Member] USD ($)	Feb. 28, 2012 2007 Tax Year [Member] Brazil [Member] BRL	Dec. 31, 2012 2004 Tax Year [Member] Mexico [Member] USD ($)	Dec. 31, 2010 Diamond East Asia Limited [Member] USD ($)
Income Taxes [Line Items]
Amount of undistributed foreign earnings and profit			$ 2,000,000,000
Taxes for undistributed earnings of the foreign subsidiaries		24,000	24,000														15,000,000
Number of new drillships		3
Reversal of income taxes that had provided in prior periods for earnings of DEAL		15,000,000
NOL carryforwards			24,100,000
Deferred tax asset relates to NOL carryforwards			7,500,000
Tax benefit of NOL carrryforwards, Mexico			16,600,000
Valuation allowance of NOL		26,353,000	22,876,000
Portion of operating loss carryforwards expected to be realized			1,200,000
Net liability for uncertain tax positions		41,241,000	48,353,000	45,936,000	27,008,000	7,000,000	7,200,000	55,400,000	48,400,000
Net unrecognized tax benefits would affect the effective tax rate		41,200,000	48,400,000	45,900,000
Total tax assessment including interest and penalty										26,000,000	1,500,000		24,400,000	17,000,000	35,100,000	22,900,000
Recognition of tax benefits from uncertain tax positions										Greater than 50% likelihood of being realized upon settlement is to be recognized
Accrued liabilities related to income tax examination										12,900,000
Accrued interest related to income tax examination										3,600,000
Accrued penalties related to income tax examination										3,200,000
Reduction related to statute of limitation expirations		3,744,000										6,800,000				4,400,000
Interest related to income tax examination												1,100,000				2,600,000
Penalties related to income tax examination												2,000,000				200,000
Reduction in tax expense	$ 28,000,000