Capital and Operating Leases (Details Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Leases [Abstract]
Rent expense	$ 38	$ 34	$ 36
Pipeline System Lease [Member]
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years
Percent ownership in pipeline	40.00%
Minimum [Member] | Energy Services Agreement [Member]
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	3 years
Maximum | Energy Services Agreement [Member]
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years