Description of Business and Basis of Presentation - Additional Information (Detail)	Dec. 31, 2014
Business Acquisition [Line Items]
Ownership interest percentage by parent	100.00%
Investments in Greater Than 20% [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Investments in Less Than 20% [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Phillips 66 [Member]
Business Acquisition [Line Items]
Ownership interest percentage by parent	50.00%
Spectra Energy [Member]
Business Acquisition [Line Items]
Ownership interest percentage by parent	50.00%
DCP Midstream, LLC [Member]
Business Acquisition [Line Items]
Ownership interest percentage by parent	21.40%