Debt CCFC Term Loans (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt Issuance Costs, Net			$ 112
Long-term Debt		$ 11,213	10,156	$ 11,213
Gains (Losses) on Extinguishment of Debt			28	(38)	$ (25)
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 984	$ 974	$ 984
Debt Instrument, Interest Rate, Effective Percentage	[1]	4.60%	4.90%	4.60%
New CCFC Term Loans [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net		$ 13		$ 13
Debt Instrument, Face Amount		$ 1,000		$ 1,000
Long Term Debt net of Original Issuance Disount		99.875%
Percentage of principal amount of Term Loan to be paid quarterly			0.25%
Minimum Partial Prepayment Amount			$ 1
CCFC Term Loans [Member]
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt		$ (12)
Federal Funds Effective Rate [Member] | New CCFC Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.50%
Eurodollar Rate For A One-Month Interest Period [Member] | New CCFC Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Prime Rate Or The Eurodollar Rate For a One Month Interest Period [Member] | New CCFC Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.50%
London Interbank Offered Rate (LIBOR) [Member] | New CCFC Term Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.50%

[1] Our weighted average interest rate calculation includes the amortization of debt issuance costs and debt discount.