v3.3.1.900

Debt (Textuals) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 08, 2016
Debt Instrument [Line Items]
Maximum Remaining Lease Term				36 years
Lease Assets, Historical Cost		$ 877		$ 877	$ 933
Lease Assets, Accumulated Depreciation		390		390	395
Gains (Losses) on Extinguishment of Debt				$ (40)	$ (346)	$ (144)
First Lien Notes 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				10.00%
Gains (Losses) on Extinguishment of Debt		(7)	$ (19)
Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Repayment time for drawings under letters of credit				2 days
Excess amount of asset sales requiring mandatory prepayments				$ 3,000
Corporate Revolving Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable margin range percentage above base rate				1.00%
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates				2.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.25%
Corporate Revolving Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable margin range percentage above base rate				1.25%
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates				2.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.50%
CDHI [Member]
Debt Instrument [Line Items]
Letter of Credit Total		300		$ 300
One Month [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				1 month
Two Months [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				2 months
Three Months [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				3 months
Six Months [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				6 months
Nine Months [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				9 months
Twelve Months [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings				12 months
Federal Funds Effective Rate [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.50%
Subsequent Event [Member] | Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net	$ 178
Line of Credit Facility, Maximum Borrowing Capacity							$ 1,678
Increase in Letter of Credit Sublimit							250
Total Letter of Credit Sublimit							$ 1,000
Extension of Line of Credit Revolver	2 years
Granite Ridge Energy LLC [Member]
Debt Instrument [Line Items]
Proceeds from 2023 First Lien Term Loan utilize for Acquisition of Granite Ridge Energy LLC		$ 325		$ 325

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