Debt (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Apr. 21, 2016	Dec. 31, 2015	Mar. 26, 2015	Feb. 24, 2015
Debt Instrument [Line Items]
Loss on extinguishment of debt	$ (2)	$ (19)
Deferred financing fees	12			$ 13
Long term debt net of unamortized debt issuance costs	2,114			2,175
Fair value of debt	2,251			$ 2,295
Credit facility
Debt Instrument [Line Items]
Borrowing available under credit facility	347
Outstanding lines of credit	$ 0
Interest rate at period end for line of credit facility	1.88%
Amount of letters of credit outstanding	$ 49
CGC Credit Facility CAD
Debt Instrument [Line Items]
Interest rate at period end for line of credit facility	2.15%
CGC credit facility USD
Debt Instrument [Line Items]
Borrowing available under credit facility	$ 50
8.375% senior notes due 2018
Debt Instrument [Line Items]
Repurchase of outstanding debt		350			$ 224	$ 126
Amount paid in consideration of debt repurchase					$ 242	135
6.3% senior notes due 2016
Debt Instrument [Line Items]
Repurchase of outstanding debt		$ 62
Debt instrument interest rate	6.30%			6.30%
Premiums paid on repurchased debt	$ 2
Accrued interest paid on repurchased debt	1
Amount paid in consideration of debt repurchase	$ 65
5.5% senior notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate	5.50%			5.50%
Face amount of debt						350
Deferred financing fees						$ 6
Long term debt net of unamortized debt issuance costs	$ 344
Subsequent Event [Member] | 6.3% senior notes due 2016
Debt Instrument [Line Items]
Repurchase of outstanding debt			$ 47
Premiums paid on repurchased debt			2
Accrued interest paid on repurchased debt			1
Amount paid in consideration of debt repurchase			$ 50