XML 19 R50.htm IDEA: XBRL DOCUMENT

Alternative Energy Tax Credits (Details) (USD $)	3 Months Ended					3 Months Ended			3 Months Ended
Alternative Energy Tax Credits (Details) (USD $)	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010	Mar. 31, 2012 Alternative Fuel Mixture Credits [Member]	Dec. 31, 2009 Alternative Fuel Mixture Credits [Member]	Mar. 31, 2012 Cellulosic Biofuel Tax Credits [Member]	Dec. 31, 2010 Cellulosic Biofuel Tax Credits [Member]	Dec. 31, 2009 Cellulosic Biofuel Tax Credits [Member]	Dec. 31, 2010 Amended 2009 Federal Return [Member]
Alternative Energy Tax Credits [Line Items]
Refundable tax credit per gallon					$ 0.50			$ 1.01
Cellulosic biofuel producer credits									107,000,000
Alternative energy tax credits				95,500,000		23,000,000	5,000,000
Provision for income taxes	141,583,000	21,583,000				118,500,000
Uncertain tax positions			102,000,000
Tax credits used to offset future cash tax payment	$ 144,400,000

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.