Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

Long-term Purchase Commitment [Table Text Block]

As of June 30, 2018, minimum payment obligations for natural gas supply commitments are approximately:

	(in millions)
Remaining six months of 2018	$	185
2019	264
2020	168
2021	82
2022	51
2023 and beyond	123