Revenues from Contracts with Customers (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Product and service revenues	$ 2,872	$ 2,214	$ 5,449	$ 4,589
Sales of Purchased Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	575	450	931	860
Sales of Purchased Product [Member] \| Market Optimization Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	575	450	931	860
Operating Segments [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	1,776	1,514	3,272	3,194
Operating Segments [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	1,096	700	2,177	1,395
Operating Segments [Member] \| Sales of Purchased Product [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	506	396	773	764
Operating Segments [Member] \| Sales of Purchased Product [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	69	54	158	96
Corporate & Other [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Corporate & Other [Member] \| Sales of Purchased Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Corporate & Other [Member] \| Sales of Purchased Product [Member] \| Market Optimization Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Oil [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	1,126	833	2,054	1,810
Oil [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	1,124	831	2,047	1,806
Oil [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	2	2	7	4
Oil [Member] \| Corporate & Other [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Natural Gas Liquids [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	862	544	1,547	1,057
Natural Gas Liquids [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	143	177	305	367
Natural Gas Liquids [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	719	367	1,242	690
Natural Gas Liquids [Member] \| Corporate & Other [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Natural Gas [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	305	378	906	850
Natural Gas [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	1	104	142	249
Natural Gas [Member] \| Operating Segments [Member] \| Product Revenues [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	304	274	764	601
Natural Gas [Member] \| Corporate & Other [Member] \| Product Revenues [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	0	0	0	0
Natural Gas Gathering and Processing, and Other [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	4	9	11	12
Natural Gas Gathering and Processing, and Other [Member] \| Operating Segments [Member] \| USA Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	2	6	5	8
Natural Gas Gathering and Processing, and Other [Member] \| Operating Segments [Member] \| Canadian Operations Excluding Intercompany Segment Transactions [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	2	3	6	4
Natural Gas Gathering and Processing, and Other [Member] \| Corporate & Other [Member]
Disaggregation of Revenue [Line Items]
Product and service revenues	$ 0	$ 0	$ 0	$ 0