Derivatives and Risk Management Activities (Details)	Mar. 31, 2013 bbl
Commodity Price Risk Hedging:
Storage capacity owned but not used in entity's transportation operations (in barrels)	97,000,000
Derivative hedges to manage the risk of not utilizing storage capacity (in barrels per month)	2,100,000
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	7,800,000
Net long position associated with crude oil purchases
Commodity Price Risk Hedging:
Net derivative positions per day (in barrels)	319,400
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	9,600,000
Net short spread position hedging anticipated crude oil lease gathering purchases
Commodity Price Risk Hedging:
Net derivative positions per day (in barrels)	14,600
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	13,700,000
WTS/WTI crude oil basis swaps related to anticipated sales of crude oil
Commodity Price Risk Hedging:
Net derivative positions per day (in barrels)	12,800
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	3,200,000
Average butane/WTI spread positions
Commodity Price Risk Hedging:
Net derivative positions per day (in barrels)	2,800
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	1,000,000
Long natural gas swaps position for anticipated base gas requirements
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	2,900,000
Short natural gas swap position related to anticipated natural gas sales
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	26,500,000
PLA Average crude oil net short position futures and swaps
Commodity Price Risk Hedging:
Net derivative positions per day (in barrels)	1,900
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	1,900,000
PLA Crude oil long call option position
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	500,000
PLA Crude oil long put option position
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	200,000
Long natural gas swaps position for natural gas purchases
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	16,100,000
Short propane position related to subsequent sale of products
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	2,800,000
Short Butane position related to subsequent sale of products
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	800,000
Short WTI position related to subsequent sale of products
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	300,000
Long power position for power supply requirements
Commodity Price Risk Hedging:
Crude oil, NGL or natural gas inventory hedged (in barrels, Mcf or megawatt hours)	700,000