Long-Term Debt (Narrative) (Details) (USD $)	1 Months Ended	6 Months Ended						6 Months Ended									1 Months Ended		1 Months Ended	6 Months Ended
	Jan. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	May 31, 2011	Mar. 31, 2011	Dec. 31, 2010	Mar. 31, 2010	Jun. 30, 2011 Maximum [Member] Helix Term Loan [Member]	Jun. 30, 2011 Maximum [Member] Helix Revolving Loans [Member]	Jun. 30, 2011 Minimum [Member] Helix Term Loan [Member]	Jun. 30, 2011 Minimum [Member] Helix Revolving Loans [Member]	Jun. 30, 2011 Helix Term Loan [Member]	Jun. 30, 2010 Helix Term Loan [Member]	Jul. 31, 2006 Helix Term Loan [Member]	Jun. 30, 2011 Helix Revolving Loans [Member]	Jul. 31, 2006 Helix Revolving Loans [Member]	Dec. 31, 2007 Senior Unsecured Notes [Member]	Jun. 30, 2011 Senior Unsecured Notes [Member]	Mar. 31, 2005 Convertible Senior Notes [Member]	Jun. 30, 2011 Convertible Senior Notes [Member]		Jun. 30, 2011 MARAD Debt [Member]		Jun. 30, 2011 Letters of Credit [Member]	Jun. 30, 2011 Helix [Member]	Dec. 31, 2010 Helix [Member]
Unsecured letters of credit		$ 48,800,000																						$ 48,800,000
Long-term debt, noncurrent		1,239,893,000				1,347,753,000						296,250,000			0		550,000,000	550,000,000		285,886,000	[1]	107,757,000			1,132,136,000	1,237,587,000
Long-term debt, Carrying Value		1,261,766,000																550,000,000	300,000,000	300,000,000	[2]	112,516,000	[3]
Long Term Debt														835,000,000
Debt instrument interest rate																	9.50%					4.93%
Stated maturity Year																	2016			March 2025		February 2027
Original borrowing capacity		600,000,000		435,000,000												300,000,000
Cash and cash equivalents plus available capacity under revolving credit facility																		500,000,000		400,000,000
Margin range								3.50%	3.50%	3.25%	2.50%
Base rate range								2.50%	2.50%	2.25%	1.50%
Average interest rate												3.20%	2.90%
Revolving credit facility available		551,200,000
Borrowing under revolving credit facility		109,400,000	0
Investments in Subsidiaries Permitted by Credit Agreement, Excluding Loan Party Subsidiaries and Subsidiaries With Pledged Equity Interests		200,000,000		150,000,000
Repurchases and Redemptions Permitted Under Credit Agreement, Common Stock, Value															50,000,000
Interest rate swap	200,000,000	200,000,000
Interest rate swap maximum term in years	two
Debt instrument issued percentage																			100.00%
Effective interest rate																				6.60%
Per share conversion price					$ 32.14		$ 32.14
Convertible senior notes are convertible into shares																				13,303,770
Debt instrument, frequency of periodic payment																						semi-annual
Debt collateral percentage		50.00%
Deferred Finance Costs, Net		30,127,000				25,697,000
Amortization of deferred financing costs		4,777,000	3,768,000									800,000
Repayment of revolving credit facility		$ (109,400,000)	$ 0									$ 109,400,000

[1] Beginning in December 2012, the holders may require us to repurchase the notes or we may at our own option elect to repurchase the notes. The notes will mature in March 2025.

[2] Amount excludes the $14.1 million of unamortized discount recorded on the Convertible Senior Notes at June 30, 2011.

[3] The estimated fair value of all debt, other than MARAD Debt, was determined using level 1 inputs using the market approach. The fair value of the MARAD debt was determined using a third party evaluation of the remaining average life and outstanding principal balance of the MARAD indebtedness as compared to other governmental obligations in the market place with similar terms. The fair value of the MARAD debt was estimated using level 2 fair value inputs using the cost approach.