Debt (Details Textual) - USD ($)		3 Months Ended		6 Months Ended
	Feb. 12, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Mar. 26, 2015	Feb. 24, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt instrument interest rate					10.00%
Loss on extinguishment of debt				$ 19,000,000	$ 0
Long-term debt		$ 2,188,000,000		2,188,000,000				$ 2,209,000,000
Deferred financing fees		15,000,000		15,000,000
Fair value of debt		2,315,000,000		2,315,000,000				$ 2,338,000,000
Credit facility
Debt Instrument [Line Items]
Borrowing available under credit facility		352,000,000		352,000,000
Outstanding lines of credit		$ 0		$ 0
Interest rate at period end for line of credit facility		2.03%		2.03%
Amount of letters of credit outstanding		$ 53,000,000		$ 53,000,000
CGC credit facility USD
Debt Instrument [Line Items]
Borrowing available under credit facility		$ 50,000,000		$ 50,000,000
Interest rate at period end for line of credit facility		2.74%		2.74%
8.375% senior notes due 2018
Debt Instrument [Line Items]
Repurchase of outstanding debt		$ 350,000,000		$ 350,000,000		$ 224,000,000	$ 126,000,000
Debt instrument interest rate		8.375%		8.375%				8.375%
Amount paid in consideration of debt repurchase						$ 242,000,000	135,000,000
Long-term debt		$ 0		$ 0				$ 350,000,000
5.5% senior notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate		5.50%		5.50%				5.50%
Face amount of debt							350,000,000
Long-term debt		$ 350,000,000		$ 350,000,000			$ 350,000,000	$ 0
Deferred financing fees		6,000,000		$ 6,000,000
Redemption price percentage				102.75%
Premium associated with contractual redemption of notes upon change in control				101.00%
Ship mortgage facility
Debt Instrument [Line Items]
Long-term debt		0		$ 0				$ 21,000,000
Voluntary payment of debt	$ 2,000,000
Repayment of debt		$ 18,000,000	$ 1,000,000