Debt (Details) (USD $)	9 Months Ended						9 Months Ended					9 Months Ended
	Sep. 30, 2011	Dec. 15, 2011	Dec. 03, 2011	Jun. 03, 2011	Dec. 31, 2010	Mar. 31, 2010	Sep. 30, 2011 Revolving Credit Facility [Member]	Sep. 30, 2011 U.S. Government Guaranteed Long Term Financing [Member] Liftboat	Sep. 30, 2011 Unsecured Senior Notes Due Two Thousand Fourteen [Member]	Sep. 30, 2011 Unsecured Senior Exchangeable Notes Due Two Thousand Twenty Six [Member]	Dec. 31, 2010 Unsecured Senior Exchangeable Notes Due Two Thousand Twenty Six [Member]	Sep. 30, 2011 Unsecured senior notes due two thousand nineteen [Member]	Apr. 30, 2011 Unsecured senior notes due two thousand nineteen [Member]
Line of credit facility (Textual) [Abstract]
Line of credit letters of credit outstanding							$ 9,400,000
Revolving Borrowing capacity, current							400,000,000
Revolving borrowing capacity if option is exercised							550,000,000
Revolving credit facility, Outstanding							0
Debt (Textual) [Abstract]
Debt instrument, outstanding								13,000,000	300,000,000	400,000,000
Number of 245-Foot class liftboats								2
Unsecured Senior Notes, outstanding												500,000,000
Debt instrument, percentage	1.50%							6.45%	6.875%	1.50%		6.375%	6.375%
Effective interest rate for amortize debt										6.89%
Unamortized discount on Exchangeable Note										4,400,000	19,700,000
Debt Maturity Date	Jul. 20, 2014							Sep. 03, 2027	Sep. 01, 2014	Dec. 15, 2026		May 01, 2019
Debt (Additional Textual) [Abstract]
Principal payable, semi annual installments			405,000	405,000
Interest payments at a fixed rate	6.875%					6.875%
Variable interest rate, Adjustment	90 days
Interest rate swap agreement for a notional	150,000,000					150,000,000
Amended Interest rate on Exchangeable Note		1.25%
Initial exchange rate of common stock per $1,000 principal amount of notes	21.9414
Principal amount of notes for initial exchange rate of common stock	1,000
Initial exchange price of per share of common stock	$ 45.58
Percentage of premium over the closing share price at date of issuance represented by exchange price	35.00%
Condition one for exchange of common stock	during any fiscal quarter (and only during such fiscal quarter), if the last reported sale price of the Company’s common stock is greater than or equal to 135% of the applicable exchange price of the notes for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the preceding fiscal quarter
Exchange price rate of notes for condition one of Exchange	135.00%
Trading period for exchange price rate of notes for condition one of exchange	20 days
Consecutive trading period for exchange price rate of notes for condition one of exchange	30 days
Business period for condition two of exchange	5 days
Maximum percentage of product of last reported sale price of company common stock for condition two of exchange	95.00%
Consecutive trading period before business period for condition two of exchange	10 days
Condition two for exchange of common stock	prior to December 15, 2011, during the five business-day period after any ten consecutive trading-day period (the “measurement period”) in which the trading price of $1,000 principal amount of notes for each trading day in the measurement period was less than 95% of the product of the last reported sale price of the Company’s common stock and the exchange rate on such trading day
Purchase price payable for redemption of exchangeable notes	100.00%
Approximate number of shares that can be purchased by exercise of call options	8,800,000
Approximate number of shares that can be purchased by exercise of warrants	8,800,000
Strike price of common stock, per share	$ 45.58
Price of common stock, per share	$ 59.42
Counterparty interest in call option and warrant transaction	50.00%
Redeem unsecured senior exchangeable notes	400,000,000
Amount available under revolving credit facility					216,000,000
Costs associated with the issuance of unsecured senior notes	$ 9,600,000
Mortgages	2 liftboats