Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Property, Plant and Equipment

Property, plant and equipment consisted of the following assets:

(millions)	Estimated Useful Lives	December 31, 2020			December 31, 2019
Electric generation	21-56 years	$	5,694		$	5,370
Electric transmission	28-77 years		1,008			940
Electric distribution	14-56 years		2,859			2,732
Gas transmission and distribution	16-77 years		2,076			1,848
General plant and other	8-43 years		723			675
Total cost			12,360			11,565
Less accumulated depreciation			(3,712	)		(3,472	)
Construction work in progress			1,472			1,038
Total property, plant and equipment, net		$	10,120		$	9,131