Debt - Components (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Short-term debt:
Total short-term debt	$ 831	$ 504
Long-term debt:
PAA senior notes, net of unamortized discounts and debt issuance costs	9,071	8,939
Noncurrent portion of other long-term debt	311	248
Total long-term debt	9,382	9,187
Total debt	10,213	9,691
Line of Credit \| PAA commercial paper notes
Short-term debt:
Short-term notes and borrowings	$ 547	$ 93
Weighted average interest rate, short-term	0.70%	2.20%
Line of Credit \| PAA senior secured hedged inventory facility
Short-term debt:
Short-term notes and borrowings	$ 167	$ 325
Weighted average interest rate, short-term	1.20%	2.70%
Other
Short-term debt:
Total short-term debt	$ 117	$ 86
PAA senior notes
Long-term debt:
Unamortized discounts and debt issuance costs	(62)	(61)
PAA senior notes, net of unamortized discounts and debt issuance costs	9,071	8,939
Senior notes repurchase amount	17
Debt instrument face value	9,100	9,000
PAA senior notes \| Other income/(expense), net
Long-term debt:
Gain on repurchase of senior notes	3
PAA senior notes \| Level 2
Long-term debt:
Debt instrument fair value	9,900	9,300
PAA senior notes \| 5.00% senior notes due February 2021
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 0	600
Debt instrument, interest rate (as a percent)	5.00%
PAA senior notes \| 3.65% senior notes due June 2022
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750	750
Debt instrument, interest rate (as a percent)	3.65%
PAA senior notes \| 2.85% senior notes due January 2023
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 400	400
Debt instrument, interest rate (as a percent)	2.85%
PAA senior notes \| 3.85% senior notes due October 2023
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 700	700
Debt instrument, interest rate (as a percent)	3.85%
PAA senior notes \| 3.60% senior notes due November 2024
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750	750
Debt instrument, interest rate (as a percent)	3.60%
PAA senior notes \| 4.65% senior notes due October 2025
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 1,000	1,000
Debt instrument, interest rate (as a percent)	4.65%
PAA senior notes \| 4.50% senior notes due December 2026
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750	750
Debt instrument, interest rate (as a percent)	4.50%
PAA senior notes \| 3.55% senior notes due December 2029
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 1,000	$ 1,000
Debt instrument, interest rate (as a percent)	3.55%	3.55%
Debt instrument face value		$ 1,000
PAA senior notes \| 3.80% senior notes due September 2030
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750	0
Debt instrument, interest rate (as a percent)	3.80%
Debt instrument face value	$ 750
PAA senior notes \| 6.70% senior notes due May 2036
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 250	250
Debt instrument, interest rate (as a percent)	6.70%
PAA senior notes \| 6.65% senior notes due January 2037
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 600	600
Debt instrument, interest rate (as a percent)	6.65%
PAA senior notes \| 5.15% senior notes due June 2042
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 499	500
Debt instrument, interest rate (as a percent)	5.15%
PAA senior notes \| 4.30% senior notes due January 2043
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 348	350
Debt instrument, interest rate (as a percent)	4.30%
PAA senior notes \| 4.70% senior notes due June 2044
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 687	700
Debt instrument, interest rate (as a percent)	4.70%
PAA senior notes \| 4.90% senior notes due February 2045
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 649	650
Debt instrument, interest rate (as a percent)	4.90%
Term loan \| GO Zone Term Loans
Long-term debt:
Noncurrent portion of other long-term debt	$ 199	199
Debt issuance costs	$ 1	$ 1
Weighted average long term debt interest rate	1.30%	2.60%
Other long-term debt
Long-term debt:
Noncurrent portion of other long-term debt	$ 112	$ 49

Amount of short-term and long-term debt and lease obligation.

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