Ventures and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 851		$ 780		$ 998	$ 984
Property, plant and equipment	3,685		3,733
Other assets	343		377
Total assets	8,626		8,818
Trade payables	664		757
Current liabilities(2)	1,195		1,338
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents	1		1
Property, plant and equipment	620		535
Other assets	29		24
Total assets	650	[1]	560	[1]
Trade payables	1		0
Current liabilities(2)	33	[2]	40	[2]
Long-term debt	5		0
Total liabilities	39		40
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment	93		96
Trade payables	49		43
Capital Lease Obligations, Current	9		9
Long-term debt	122		125
Total liabilities	180		177
Maximum exposure to loss	$ 291		$ 291

[1] Assets can only be used to settle the obligations of Fairway.

[2] Amounts owed by Fairway for reimbursement of expenditures.