Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Parent, total ownership percentage	60.00%
Parent, limited partner ownership percentage	58.00%
Parent, general partner ownership percentage	2.00%
Purchase Price Allocation
Purchase price allocation, gross	$ 1,500,000
Purchase price allocation, property, plant and equipment, estimated useful lIfe	40 years
Purchase price allocation, depreciation	$ 35,000
Purchase price allocation, remaining allocation	700,000
Schedule of Equity Method Investments [Line Items]
Equity method investment, distributions	7,600	$ 9,100	$ 11,500
Equity method investment, return of capital	2,015	2,333	1,438
Capitalized Interest Costs, Including Allowance for Funds Used During Construction [Abstract]
Allowance for funds used during construction, borrowed	14,600	6,300	5,300
Allowance for funds used during construction, equity	48,435	18,701	$ 13,299
Inventory Disclosure [Abstract]
Gas in storage, LIFO	$ 0	497
Excess of replacement cost over LIFO cost		$ 100
Gathering facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	1.35%	1.35%	1.35%
Gathering facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	2.50%	2.50%	2.50%
Storage facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	2.10%	2.10%	2.10%
Storage facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	2.25%	2.25%	2.25%
Onshore transmission facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	2.61%	2.61%	2.61%
Onshore transmission facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	5.00%	5.00%	5.00%
Offshore transmission facilities | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	1.20%	1.20%	1.20%
Offshore transmission facilities | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation rates	1.20%	1.20%	1.20%
Cardinal Pipeline Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	45.00%	45.00%
Pine Needle LNG Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	35.00%	35.00%