Variable Interest Entities - Additional Information (Detail) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended					1 Months Ended			3 Months Ended			12 Months Ended		1 Months Ended
	Jun. 30, 2000	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Jun. 30, 2000 Limited Liability Company II [Member]	Jun. 30, 2000 Limited Liability Company [Member]	Jun. 30, 2000 Limited Liability Company [Member] Limited Liability Company II [Member] USD ($)	Dec. 31, 2013 Limited Liability Company [Member] Limited Liability Company II [Member] USD ($)	Dec. 31, 2012 Limited Liability Company [Member] Limited Liability Company II [Member] USD ($)	Apr. 30, 2010 Low-Income Housing Properties [Member] USD ($)	Dec. 31, 2013 Low-Income Housing Properties [Member] USD ($)	Dec. 31, 2012 Low-Income Housing Properties [Member] USD ($)	Dec. 31, 2013 Investment in Recycling and Waste-to-Energy [Member] USD ($)	Dec. 31, 2013 Investment in Recycling and Waste-to-Energy [Member] GBP (£)	Mar. 31, 2012 Investment in Recycling and Waste-to-Energy [Member]	Dec. 31, 2013 Investment in Recycling and Waste-to-Energy [Member] USD ($)	Dec. 31, 2013 Investment in Recycling and Waste-to-Energy [Member] GBP (£)	Jan. 31, 2011 Investment in Refined Coal Facility [Member] USD ($)	Dec. 31, 2013 Investment in Refined Coal Facility [Member] USD ($)	Dec. 31, 2012 Investment in Refined Coal Facility [Member] USD ($)
Business Acquisition [Line Items]
Percentage of ownership in LLC's					0.25%	0.50%									50.00%
Percentage of variable interest entities owned by other companies					99.75%	99.50%
Total initial investment by other companies							$ 167
Under the LLC agreements, the LLC shall be dissolved upon the occurrence of any of the following events	(i) a written decision of all members of the LLCs; (ii) December 31, 2063; (iii) a court's dissolution of the LLCs; or (iv) the LLCs ceasing to own any interest in the waste-to-energy facilities.
Reporting entity percentage of interest in earnings of variable interest entity after achieving targeted returns							80.00%
Other companies percentage of interest in earnings of variable interest entity after achieving targeted returns							20.00%
Net property and equipment								284	296
Noncontrolling interests		295	321					239	245
Expense recognized for other companies' noncontrolling interests in LLCs earnings		43	45	50
Expected cost to construct Waste-to-Energy LLC facility													331	200		331	200
Total commitment													94	57		94	57
Note receivables balance from the LLC																18	11
Investment balance		437	443								129	153	1			1			27	19
Cash payments to acquire equity method investment										6								48
Consideration for investment										221
Value of notes payable included in consideration for investment										215
Equity method investments debt balance											128	152
Variable interest entities primary beneficiary trust fair value assets		125	125
Carrying value of restricted trust funds and escrow accounts for which company is not the sole beneficiary specifically for future settlement of landfill and environmental remediation liabilities		$ 110	$ 110