Statements of Cash Flows (Unaudited) - MEC - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 2,285	$ 1,786
Adjustments to reconcile net income to net cash flows from operating activities:
Allowance for equity funds	(56)	(72)
Deferred income taxes and amortization of investment tax credits	613	288
Other, net	(26)	18
Changes in other operating assets and liabilities, net of effects from acquisitions:
Trade receivables and other assets	(254)	(783)
Pension and other postretirement benefit plans	(33)	(45)
Accrued property, income and other taxes, net	76	(605)
Accounts payable and other liabilities	187	240
Net cash flows from operating activities	4,232	1,854
Cash flows from investing activities:
Capital expenditures	(2,848)	(2,793)
Purchases of marketable securities	(185)	(272)
Proceeds from sales of marketable securities	163	256
Other, net	(53)	58
Net cash flows from investing activities	(2,975)	(3,838)
Cash flows from financing activities:
Net proceeds from (repayments of) short-term debt	245	(920)
Other, net	(28)	(39)
Net cash flows from financing activities	(1,204)	2,798
Net change in cash and cash equivalents and restricted cash and cash equivalents	55	802
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	1,445	1,268
Cash and cash equivalents and restricted cash and cash equivalents at end of period	1,500	2,070
MEC
Cash flows from operating activities:
Net income (loss)	360	360
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	416	351
Amortization of utility plant to other operating expenses	17	17
Allowance for equity funds	(14)	(17)
Deferred income taxes and amortization of investment tax credits	196	131
Settlements of asset retirement obligations	(19)	(25)
Other, net	11	8
Changes in other operating assets and liabilities, net of effects from acquisitions:
Trade receivables and other assets	(275)	(1)
Inventories	41	(31)
Pension and other postretirement benefit plans	0	(11)
Accrued property, income and other taxes, net	56	(409)
Accounts payable and other liabilities	(68)	(47)
Net cash flows from operating activities	721	326
Cash flows from investing activities:
Capital expenditures	(720)	(824)
Purchases of marketable securities	(109)	(210)
Proceeds from sales of marketable securities	105	202
Other, net	(2)	14
Net cash flows from investing activities	(726)	(818)
Cash flows from financing activities:
Net proceeds from (repayments of) short-term debt	0	195
Other, net	(2)	(1)
Net cash flows from financing activities	(2)	194
Net change in cash and cash equivalents and restricted cash and cash equivalents	(7)	(298)
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	45	330
Cash and cash equivalents and restricted cash and cash equivalents at end of period	$ 38	$ 32