Debt (Details 3) (USD $) In Millions, unless otherwise specified	9 Months Ended						9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended
	Sep. 30, 2012 Senior secured hedged inventory facility	Jun. 30, 2012 Senior secured hedged inventory facility	May 31, 2012 Senior secured hedged inventory facility	Sep. 30, 2012 Letters of credit	Jun. 30, 2012 Letters of credit	May 31, 2012 Letters of credit	Sep. 30, 2012 PNG senior unsecured revolving credit facility maturing in August 2016	Jun. 30, 2012 PNG senior unsecured revolving credit facility maturing in August 2016	May 31, 2012 PNG senior unsecured revolving credit facility maturing in August 2016	Sep. 30, 2012 PNG senior unsecured revolving credit facility maturing in August 2016 Minimum extension	Dec. 31, 2011 Terminated PAA senior unsecured 364-day revolving credit agreement	Sep. 30, 2012 Senior secured hedged inventory debt facility scheduled to mature in August 2014 Minimum extension
Debt
Borrowing capacity	$ 1,400	$ 1,400	$ 850	$ 400	$ 400	$ 250	$ 350	$ 350	$ 250		$ 1,200
Period for activation of credit facility											6 months
Tenure of credit facility											364 days
Maximum borrowing capacity	$ 1,900	$ 1,900					$ 550	$ 550
Credit facility extensions available										1		1
Maturity date extension	1 year
Extension period subject to approval	1 year						1 year