Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities
Net income	$ 1,889	$ 2,039
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	1,702	2,255
Deferred income taxes and amortization of investment tax credits	1,008	240
Net fair value changes related to derivatives	360	(281)
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	90	(49)
Other non-cash operating activities	703	468
Changes in assets and liabilities:
Accounts receivable	3	(172)
Inventories	(44)	(52)
Accounts payable, accrued expenses and other current liabilities	(400)	(53)
Option premiums paid, net	59	(101)
Counterparty collateral (posted) received, net	(807)	289
Income taxes	532	310
Pension and non-pension postretirement benefit contributions	(2,089)	(740)
Other assets and liabilities	(89)	(41)
Net cash flows provided by operating activities	2,917	4,112
Cash flows from investing activities
Capital expenditures	(2,972)	(2,382)
Proceeds from nuclear decommissioning trust fund sales	3,120	2,756
Investment in nuclear decommissioning trust funds	(3,293)	(2,864)
Acquisition of Exelon Wind	(380)
Proceeds from sales of investments	0	0
Purchases of investments	0	0
Change in restricted cash	(532)	427
Other investing activities	26	26
Net cash flows provided by (used in) investing activities	(4,031)	(2,037)
Cash flows from financing activities
Changes in short-term debt	462	(90)
Issuance of long-term debt	1,199	1,398
Retirement of long-term debt	(3)	(827)
Retirement of long-term debt of variable interest entity	0	(806)
Dividends paid on common stock	(1,044)	(1,042)
Proceeds from employee stock plans	26	34
Other financing activities	(67)	(17)
Net cash flows used in financing activities	573	(1,350)
Increase (decrease) in cash and cash equivalents	(541)	725
Cash and cash equivalents at beginning of period	1,612	2,010
Cash and cash equivalents at end of period	1,071	2,735
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	1,325	1,548
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	1,131	987
Impairment of long-lived assets	0	0
Deferred income taxes and amortization of investment tax credits	336	409
Net fair value changes related to derivatives	360	(281)
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	90	(49)
Other non-cash operating activities	362	164
Changes in assets and liabilities:
Accounts receivable	(165)	(11)
Receivables from and payables to affiliates, net	210	76
Inventories	(32)	(50)
Accounts payable, accrued expenses and other current liabilities	(1)	(162)
Option premiums paid, net	59	(101)
Counterparty collateral (posted) received, net	(804)	443
Income taxes	268	(13)
Pension and non-pension postretirement benefit contributions	(952)	(345)
Other assets and liabilities	(65)	(52)
Net cash flows provided by operating activities	2,122	2,563
Cash flows from investing activities
Capital expenditures	(1,865)	(1,405)
Proceeds from nuclear decommissioning trust fund sales	3,120	2,756
Investment in nuclear decommissioning trust funds	(3,293)	(2,864)
Acquisition of Exelon Wind	(380)
Change in restricted cash	0	3
Other investing activities	(3)	9
Net cash flows provided by (used in) investing activities	(2,421)	(1,501)
Cash flows from financing activities
Changes in short-term debt	72
Issuance of long-term debt	0	898
Retirement of long-term debt	(2)	(214)
Distribution to member	(61)	(623)
Contributions from member	30	3
Other financing activities	(53)	(16)
Net cash flows used in financing activities	(14)	48
Increase (decrease) in cash and cash equivalents	(313)	1,110
Cash and cash equivalents at beginning of period	456	1,099
Cash and cash equivalents at end of period	143	2,209
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	295	246
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	405	387
Deferred income taxes and amortization of investment tax credits	527	199
Other non-cash operating activities	210	162
Changes in assets and liabilities:
Accounts receivable	(4)	(72)
Receivables from and payables to affiliates, net	(13)	(69)
Inventories	(11)	(2)
Accounts payable, accrued expenses and other current liabilities	(160)	224
Counterparty collateral (posted) received, net	(3)	(154)
Income taxes	211	61
Pension and non-pension postretirement benefit contributions	(871)	(254)
Other assets and liabilities	29	(86)
Net cash flows provided by operating activities	615	642
Cash flows from investing activities
Capital expenditures	(758)	(686)
Change in restricted cash	(536)
Other investing activities	18	16
Net cash flows provided by (used in) investing activities	(1,276)	(670)
Cash flows from financing activities
Changes in short-term debt	0	(90)
Issuance of long-term debt	1,199	500
Retirement of long-term debt	(1)	(213)
Contributions from parent	0	2
Dividends paid on common stock	(225)	(225)
Other financing activities	(6)	(3)
Net cash flows used in financing activities	967	(29)
Increase (decrease) in cash and cash equivalents	306	(57)
Cash and cash equivalents at beginning of period	50	91
Cash and cash equivalents at end of period	356	34
PECO Energy Co [Member]
Cash flows from operating activities
Net income	314	303
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	150	859
Deferred income taxes and amortization of investment tax credits	181	(405)
Other non-cash operating activities	74	85
Changes in assets and liabilities:
Accounts receivable	241	(104)
Receivables from and payables to affiliates, net	(217)	(12)
Inventories	0	2
Accounts payable, accrued expenses and other current liabilities	24	(20)
Income taxes	27	243
Pension and non-pension postretirement benefit contributions	(110)	(68)
Other assets and liabilities	(28)	36
Net cash flows provided by operating activities	656	919
Cash flows from investing activities
Capital expenditures	(321)	(358)
Changes in Exelon intercompany money pool	(91)	0
Change in restricted cash	(2)	412
Other investing activities	12	7
Net cash flows provided by (used in) investing activities	(402)	61
Cash flows from financing activities
Changes in short-term debt	0	0
Issuance of long-term debt	0	0
Retirement of long-term debt of variable interest entity	0	(806)
Retirement of long-term debt to financing affiliates	0	0
Contributions from parent	18	1
Dividends paid on common stock	(268)	(178)
Dividends paid on preferred securities	(3)	(3)
Repayment of receivable from parent	0	135
Other financing activities	(5)	0
Net cash flows used in financing activities	(258)	(851)
Increase (decrease) in cash and cash equivalents	(4)	129
Cash and cash equivalents at beginning of period	522	303
Cash and cash equivalents at end of period	$ 518	$ 432