Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities
Net income	$ 1,288	$ 1,194
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	1,114	1,455
Deferred income taxes and amortization of investment tax credits	590	(373)
Net fair value changes related to derivatives	264	(123)
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	(51)	59
Other non-cash operating activities	378	278
Changes in assets and liabilities:
Accounts receivable	0	(229)
Inventories	17	1
Accounts payable, accrued expenses and other current liabilities	(486)	(239)
Option premiums paid, net	38	(15)
Counterparty collateral (posted) received, net	(494)	(172)
Income taxes	691	661
Pension and non-pension postretirement benefit contributions	(2,089)	(119)
Other assets and liabilities	(247)	(9)
Net cash flows provided by operating activities	1,013	2,369
Cash flows from investing activities
Capital expenditures	(1,985)	(1,584)
Proceeds from nuclear decommissioning trust fund sales	1,657	1,799
Investment in nuclear decommissioning trust funds	(1,772)	(1,897)
Change in restricted cash	(2)	(6)
Other investing activities	28	30
Net cash flows provided by (used in) investing activities	(2,074)	(1,658)
Cash flows from financing activities
Changes in short-term debt	140	134
Issuance of long-term debt	599	0
Retirement of long-term debt	(2)	(615)
Retirement of long-term debt of variable interest entity	0	(402)
Dividends paid on common stock	(695)	(694)
Proceeds from employee stock plans	15	22
Other financing activities	(46)	2
Net cash flows used in financing activities	11	(1,553)
Increase (decrease) in cash and cash equivalents	(1,050)	(842)
Cash and cash equivalents at beginning of period	1,612	2,010
Cash and cash equivalents at end of period	562	1,168
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	938	943
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	735	645
Impairment of long-lived assets	0	0
Deferred income taxes and amortization of investment tax credits	298	(34)
Net fair value changes related to derivatives	264	(123)
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	(51)	59
Other non-cash operating activities	168	133
Changes in assets and liabilities:
Accounts receivable	(139)	0
Receivables from and payables to affiliates, net	223	70
Inventories	(5)	(27)
Accounts payable, accrued expenses and other current liabilities	(78)	(203)
Option premiums paid, net	38	(15)
Counterparty collateral (posted) received, net	(525)	(54)
Income taxes	270	158
Pension and non-pension postretirement benefit contributions	(952)	(65)
Other assets and liabilities	(108)	(34)
Net cash flows provided by operating activities	1,076	1,453
Cash flows from investing activities
Capital expenditures	(1,270)	(982)
Proceeds from nuclear decommissioning trust fund sales	1,657	1,799
Investment in nuclear decommissioning trust funds	(1,772)	(1,897)
Change in restricted cash	0	2
Other investing activities	(3)	3
Net cash flows provided by (used in) investing activities	(1,388)	(1,075)
Cash flows from financing activities
Issuance of long-term debt	0	0
Retirement of long-term debt	(1)	(214)
Distribution to member	0	(417)
Contributions from member	0	0
Other financing activities	(34)	2
Net cash flows used in financing activities	(35)	(629)
Increase (decrease) in cash and cash equivalents	(347)	(251)
Cash and cash equivalents at beginning of period	456	1,099
Cash and cash equivalents at end of period	109	848
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	183	125
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	270	261
Deferred income taxes and amortization of investment tax credits	184	11
Other non-cash operating activities	115	60
Changes in assets and liabilities:
Accounts receivable	(62)	(156)
Receivables from and payables to affiliates, net	(23)	(81)
Inventories	(7)	(2)
Accounts payable, accrued expenses and other current liabilities	(108)	43
Counterparty collateral (posted) received, net	31	(118)
Income taxes	321	182
Pension and non-pension postretirement benefit contributions	(871)	(16)
Other assets and liabilities	38	95
Net cash flows provided by operating activities	71	404
Cash flows from investing activities
Capital expenditures	(495)	(453)
Other investing activities	22	16
Net cash flows provided by (used in) investing activities	(473)	(437)
Cash flows from financing activities
Changes in short-term debt	0	134
Issuance of long-term debt	599	0
Retirement of long-term debt	(1)	(1)
Contributions from parent	0	0
Dividends paid on common stock	(150)	(150)
Other financing activities	(2)	0
Net cash flows used in financing activities	446	(17)
Increase (decrease) in cash and cash equivalents	44	(50)
Cash and cash equivalents at beginning of period	50	91
Cash and cash equivalents at end of period	94	41
PECO Energy Co [Member]
Cash flows from operating activities
Net income	210	176
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	98	533
Deferred income taxes and amortization of investment tax credits	91	(388)
Other non-cash operating activities	44	44
Changes in assets and liabilities:
Accounts receivable	221	(75)
Receivables from and payables to affiliates, net	(218)	27
Inventories	29	30
Accounts payable, accrued expenses and other current liabilities	(11)	(21)
Income taxes	113	323
Pension and non-pension postretirement benefit contributions	(110)	(20)
Other assets and liabilities	(108)	(74)
Net cash flows provided by operating activities	359	555
Cash flows from investing activities
Capital expenditures	(209)	(218)
Changes in Exelon intercompany money pool	(171)	0
Change in restricted cash	(2)	(14)
Other investing activities	11	10
Net cash flows provided by (used in) investing activities	(371)	(222)
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	(402)
Retirement of long-term debt to financing affiliates	0	0
Contributions from parent	0	0
Dividends paid on common stock	(184)	(115)
Dividends paid on preferred securities	(2)	(2)
Repayment of receivable from parent	0	90
Other financing activities	(5)	0
Net cash flows used in financing activities	(191)	(429)
Increase (decrease) in cash and cash equivalents	(203)	(96)
Cash and cash equivalents at beginning of period	522	303
Cash and cash equivalents at end of period	$ 319	$ 207