Assets Held for Sale or Sold (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Assets Held for Sale or Sold (Narrative) [Abstract]
Net gain on dispositions	$ 6	$ 139	$ 6	$ 261
Immingham Combined Heat and Power Plant [Member] \| Marketing and Specialties [Member]
Assets Held for Sale or Sold (Narrative) [Abstract]
Net gain on dispositions		$ 132		$ 242

Gain or loss on disposition of assets, including property, plant and equipment, and tangible and intangible assets. May also include gain or loss on disposition of equity method investments from time to time.

No definition available.

Name:	psx_GainLossOnDisposition
Namespace Prefix:	psx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration