Acquisitions Oil and Gas (Details) (Montana Natural Gas Production Assets [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
May 31, 2013	Jan. 02, 2013 MMcf
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition of oil and gas properties with proved reserves	$ 70
Proved developed reserves (volume) associated with acquisition		64.6
Estimated increase in oil and gas production		28.00%
Percent owned oil and gas production		37.00%
Havre Pipeline Company, LLC [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition of oil and gas properties with proved reserves	$ 6
Ownership percentage in gas gathering systems	82.00%

- Definition

Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

+ References+ Details