The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Dispositions (additional information) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended		12 Months Ended
	Dec. 31, 2011 Landfill Gas Facility [Member]	Dec. 31, 2012 Sanfeng [Member]	Dec. 31, 2012 Fuzhou [Member]	Apr. 16, 2012 Fuzhou [Member]	Dec. 31, 2012 Tongxing [Member]	Dec. 31, 2011 Tongxing [Member]
Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity Method Investment, Ownership Percentage		40.00%			40.00%	25.00%
Percentage Of Ownership Interests Sold				32.00%
Equity Method Investment, Realized Gain (Loss) on Disposal			$ 2
Proceeds from Sales of Business, Affiliate and Productive Assets	12
Gain (Loss) on Sale of Project	$ 9