Delivery Commitments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) bbls $ / bbl MBbls
Delivery Commitments [Line Items]
Delivery Commitments, Current (2017)	12,775
Delivery Commitments, Due In Two Years (2018)	12,775
Delivery Commitments, Due In Three Years (2019)	12,775
Delivery Commitments, Due In Four Years (2020)	9,600
Delivery Commitments, Due In Five Years (2021)	7,300
Delivery Commitments, Due Thereafter	26,800
Total Delivery Commitments	82,025
Deficiency fees | $	$ 16
Minimum [Member]
Delivery Commitments [Line Items]
Deficiency fees per barrel | $ / bbl	3.50
Maximum [Member]
Delivery Commitments [Line Items]
Deficiency fees per barrel | $ / bbl	6.50
2017 to 2025 [Member]
Delivery Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production | bbls	20,000
2017 to 2020 [Member]
Delivery Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production | bbls	15,000