Derivative Instruments (Details) In Millions, unless otherwise specified	12 Months Ended				12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2004 EUR (€)	Dec. 31, 2012 Commodity futures contracts Cash Flow Hedges USD ($) MMBTU	Dec. 31, 2011 Commodity futures contracts Cash Flow Hedges USD ($) MMBTU	Dec. 31, 2010 Commodity futures contracts Cash Flow Hedges USD ($)	Dec. 31, 2012 Commodity futures contracts Cash Flow Hedges Maximum	Dec. 31, 2012 Commodity futures contracts Cash Flow Hedges Minimum
Derivatives and Hedges
Coverage of commodity futures contracts (in MM BTUs)					7,000,000	5,100,000
Unrecognized gain (loss) included in Accumulated OCI					$ (1)	$ (6)
Period during which unrecognized loss included in Accumulated OCI will be reclassified into earnings								24 months	12 months
Commodity futures contracts loss recognized in OCI					(3)	(10)	(11)
Commodity futures contracts gain (loss) reclassified from accumulated OCI into income					(8)	(7)	(9)
Senior notes designated as net investment hedge				225
Net investment hedge gain (loss) recognized in OCI		(25)	24
Forward exchange and option agreements in various currencies	750	550
Foreign exchange contracts gain (loss) recognized in income	$ 6	$ (11)	$ 18