Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Long-term Commitments

The following is a schedule of future payments under PPAs, minimum lease payments with non-cancelable lease terms in excess of one year, and other net purchase obligations/commitments at June 30, 2018:

					Long-term Service
	Purchased		Operating		Agreements/Capital		Clause Recoverable
(millions)	Power		Leases		Projects		Commitments		Total
Year ended December 31:
2018	$	17	$	2	$	308	$	248	$	575
2019		0		2		173		230		405
2020		0		2		52		178		232
2021		0		2		26		144		172
2022		0		2		8		136		146
Thereafter		0		36		0		1,122		1,158
Total future minimum payments	$	17	$	46	$	567	$	2,058	$	2,688