Description of the Business and Basis of Presentation (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of presentation

Basis of Presentation – The consolidated financial statements include all majority-owned and controlled subsidiaries. For non-wholly-owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in a VIE in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

In relation to the Merger described above and in Note 4, ANDX’s assets, liabilities and results of operations prior to the Merger are collectively included in what we refer to as the “Predecessor” from October 1, 2018, which was the date that MPC acquired Andeavor. MPLX’s acquisition of ANDX is considered a transfer between entities under common control due to MPC’s relationship with ANDX prior to the Merger. As an entity under common control with MPC, MPLX recorded the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. Transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control. Accordingly, the accompanying financial statements and related notes of MPLX LP have been retrospectively adjusted to include the historical results of ANDX beginning October 1, 2018.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation. The accompanying consolidated financial statements of MPLX have been prepared in accordance with GAAP.