Investments (Tables)

3 Months Ended

Mar. 31, 2021

Regulated Entity, Other Assets, Noncurrent [Abstract]

Amortized Cost and Fair Value of the Trust Investments

		Amortized Cost				Fair Value
	Longest	March 31,		December 31,		March 31,		December 31,
(in millions)	Maturity Dates	2021		2020		2021		2020
Stocks	—		N/A		N/A	$	1,896	$	1,908
Municipal bonds	2054	$	1,044	$	1,013		1,212		1,218
U.S. government and agency securities	2067		683		740		754		864
Corporate bonds	2070		451		460		519		550
Short-term investments and receivables/payables1	One-year		366		281		382		293
Total		$	2,544	$	2,494	$	4,763	$	4,833

1 Short-term investments include $144 million and $138 million of repurchase agreements payable by financial institutions which earn interest, are fully secured by U.S. Treasury securities and mature by April 1, 2021 and January 4, 2021 as of March 31, 2021 and December 31, 2020, respectively.

Summary of gains and losses

	Three months ended March 31,
(in millions)	2021		2020
Gross realized gains	$	111	$	39
Gross realized loss		12		2
Net unrealized gains (losses) for equity securities		18		(376)