Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Total revenues	$ 5,952	$ 5,170	$ 4,950	$ 4,111	$ 4,996	$ 5,551	$ 6,663	$ 5,942	$ 20,182	$ 23,152	$ 43,464
Gross margin	286	419	218	349	405	394	290	449	1,272	1,539
Operating income	217	348	145	281	343	334	210	370	990	1,258	1,791
Net income	122	279	82	177	216	228	103	262	660	809	1,328
Net income/(loss) attributable to PAGP	$ (8)	$ 24	$ 42	$ 36	$ 25	$ 32	$ 30	$ 31	$ 94	$ 118	$ 70
Class A Shares
Basic net income/(loss) per Class A share (in dollars per share)	$ (0.08)	$ 0.24	$ 0.43	$ 0.37	$ 0.29	$ 0.37	$ 0.37	$ 0.37	$ 0.94	$ 1.41	$ 1.28
Diluted net income/(loss) per Class A share (in dollars per share)	(0.08)	0.24	0.40	0.37	0.29	0.37	0.37	0.37	0.94	1.41	$ 1.25
Cash distribution per Class A share (in dollars per share)	$ 0.55	$ 0.62	$ 0.62	$ 0.62	$ 0.62	$ 0.60	$ 0.59	$ 0.54	$ 2.4	$ 2.35