Equity (Issuance of Stock and Forward Sale Agreement) (Details) $ in Millions			1 Months Ended	12 Months Ended
	Oct. 26, 2020 shares	Sep. 14, 2020 shares	Nov. 30, 2017 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares	Dec. 31, 2017 USD ($)
Class of Stock [Line Items]
Antidilutive securities (in shares) | shares				27,100,000	3,000,000.0	500,000
Common stock, authorized (in shares) | shares	3,200,000,000	800,000,000		3,200,000,000	3,200,000,000
Stockholders' Equity Note, Stock Split, Conversion Ratio	4	4
NEP [Member]
Class of Stock [Line Items]
Senior unsecured convertible notes outstanding | $				$ 600			$ 300
Series A Convertible Preferred Units [Member] | NEP [Member]
Class of Stock [Line Items]
Stock sold during the period | $			$ 550