Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2017

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, 2017:

					Long-term Service
	Purchased		Operating		Agreements/Capital		Clause Recoverable
(millions)	Power		Leases		Projects		Commitments		Total
Year ended December 31:
2017	$	5	$	3	$	38	$	303	$	349
2018		10		4		11		257		282
2019		0		2		11		186		199
2020		0		2		6		163		171
2021		0		2		7		132		141
Thereafter		0		38		25		1,157		1,220
Total future minimum payments	$	15	$	51	$	98	$	2,198	$	2,362