XML 101 R69.htm IDEA: XBRL DOCUMENT v2.4.0.6
Income Taxes (Details 2) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Income Taxes      
Income before tax $ 1,039 $ 513 $ 586
Partnership earnings not subject to current Canadian tax (909) (509) (585)
Partnership earnings subject to current Canadian tax 130 4 1
Canadian federal and provincial corporate tax rate (as a percent) 27.00% 28.00% 29.00%
Income tax at statutory rate 35 1  
Current tax (benefit)/expense:      
Canadian withholding tax 12    
Canadian period tax as a result of book versus tax differences (9)   4
Canadian permanent differences between book and tax (2) (3) 9
State income tax 2 1 2
Total current tax (benefit)/expense 38 (1) 15
Deferred tax (benefit)/expense:      
State income tax, deferred (2) 1  
Canadian deferred tax (benefit)/expense as a result of book versus tax differences 9 (1) (9)
Total deferred tax (benefit)/expense 7   (9)
Total income tax (benefit)/expense 45 (1) 6
Deferred tax assets:      
Book accruals in excess of current tax deductions 18 4  
Total deferred tax assets 18 4  
Deferred tax liabilities:      
Property, plant and equipment in excess of tax values (147) (128)  
Total deferred tax liabilities (147) (128)  
Net deferred tax liabilities $ (129) $ (124)