Long-Term Debt (Narrative) (Details) (USD $)	3 Months Ended				1 Months Ended	3 Months Ended				1 Months Ended	3 Months Ended		12 Months Ended						1 Months Ended			1 Months Ended	3 Months Ended			1 Months Ended		3 Months Ended					3 Months Ended			3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2012 Convertible Senior Notes 2032 [Member]	Mar. 31, 2013 Convertible Senior Notes 2032 [Member]		Dec. 31, 2012 Convertible Senior Notes 2032 [Member]	Mar. 06, 2012 Convertible Senior Notes 2032 [Member]	Feb. 28, 2013 Helix Term Loan [Member]	Mar. 31, 2013 Helix Term Loan [Member]		Dec. 31, 2012 Helix Term Loan [Member]	Mar. 31, 2012 Helix Term Loan [Member]	Jul. 31, 2006 Helix Term Loan [Member]	Mar. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Jul. 31, 2006 Revolving Credit Facility [Member]	Feb. 28, 2013 Helix Revolving Loans [Member]	Mar. 31, 2013 Helix Revolving Loans [Member]		Mar. 31, 2012 Senior Unsecured Notes [Member]	Mar. 31, 2013 Senior Unsecured Notes [Member]	Mar. 31, 2012 Senior Unsecured Notes [Member]	Dec. 31, 2007 Senior Unsecured Notes [Member]	Feb. 28, 2013 Convertible Senior Notes 2025 [Member]	Mar. 31, 2005 Convertible Senior Notes 2025 [Member]	Dec. 31, 2012 Convertible Senior Notes 2025 [Member]	Mar. 31, 2012 Convertible Senior Notes 2025 [Member]	Mar. 31, 2013 MARAD Debt [Member]		Sep. 30, 2005 MARAD Debt [Member]	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Minimum [Member] Helix Term Loan [Member]	Mar. 31, 2013 Minimum [Member] Helix Revolving Loans [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2013 Maximum [Member] Helix Term Loan [Member]	Mar. 31, 2013 Maximum [Member] Helix Revolving Loans [Member]
Debt Instrument [Line Items]
Debt instrument interest rate					3.25%																				9.50%		3.25%					4.93%
Base Principal Amount								$ 1,000
Mandatory Prepayments Percentage													60.00%
Debt Instrument Convertible Conversion Premium Percentage									35.00%
Issuance Of Notes Percentage						100.00%
Convertible Senior Notes, shares of common stock						39.9752
Senior Unsecured Notes amount issued																									550,000,000
Unsecured letters of credit																8,000,000
Long-term debt, less current maturities	687,461,000	[1]		1,002,621,000		169,590,000					67,299,000	[2]								78,100,000	[2]		274,960,000							97,512,000
Long-term debt, Carrying Value					200,000,000						72,300,000					78,100,000				78,100,000	[3]		274,960,000				300,000,000			102,759,000	[4]
Aggregate amount of debt payment			209,500,000																					213,500,000
Payment on senior notes																						200,000,000							145,100,000
Premium on debt extinguishment																								9,500,000					1,800,000
Accrued interest on notes																								4,000,000					1,100,000
Accelerated amortization of debt discount	1,278,000		2,355,000																										3,500,000
Loss on early extinguishment of debt	2,882,000		17,127,000																				11,500,000						5,600,000
Original borrowing capacity																600,000,000		300,000,000
Spread on LIBOR																														0.20%				2.25%	1.50%		3.50%	3.50%
Revolving credit facility, outstanding															835,000,000		100,000,000
Average interest rate											3.30%			4.00%		3.00%
Revolving credit facility available																513,900,000
Debt instrument issued percentage																											100.00%
Effective interest rate						6.90%
Per share conversion price						$ 25.02
Deferred financing costs, net	19,620,000			24,338,000
Amortization of deferred financing costs	1,472,000		1,611,000								2,900,000													2,000,000					300,000
Repayment of revolving credit facility	24,473,000
Debt Instrument, Repurchase Amount																													142,200,000
Proceeds from Issuance of Debt					195,000,000
Debt percentage guaranteed																														50.00%
Closing price per share									$ 18.53
Debt Instrument, Unamortized Discount	30,410,000	[1],[5]			35,400,000	30,410,000	[5]
Expected life used to estimate fair value	6 years
Commitment fee percentage																																	2.00%			3.00%
Deferred financing costs	41,000		6,337,000
Repayments of debt	$ 294,882,000		$ 750,000							$ 293,900,000									$ 24,500,000							$ 3,500,000		$ 154,300,000
Line of Credit Facility, Commitment Fee Percentage	0.50%

[1] Beginning in March 2018, the holders of these Convertible Senior Notes may require us to repurchase these notes or we may at our own option elect to repurchase notes. These notes will mature in March 2032.

[2] Amounts reflect our remaining Term Loan debt. In February 2013, we repaid $293.9 million of our Term Loan debt and $24.5 million under our Revolving Credit Facility with the after-tax proceeds from the sale of ERT.

[3] In February 2013, we repaid $293.9 million of our Term Loans and $24.5 million under our Revolving Credit Facility with the after-tax proceeds from the sale of ERT.

[4] The estimated fair value of all debt, other than the 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 marketplace with similar terms. The fair value of the MARAD Debt was estimated using Level 2 fair value inputs using the market approach.

[5] The notes will increase to their principal amount through accretion of non-cash interest charges through March 2018 for the Convertible Senior Notes due 2032.