Retirement Benefits - Reconciliation of Level 3 Assets and Liabilities measured at Fair Value for Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		$ 14,347		$ 14,874
Fair value of net plan assets at end of year		16,791		14,347
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		2,293		2,430
Fair value of net plan assets at end of year		2,578		2,293
Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		167		122
Relating to assets still held at the reporting date		(2)		(8)
Defined Benefit Plan Purchases		69		61
Defined Benefit Plan Sales		14
Settlements	[1]	(12)		(8)
Fair value of net plan assets at end of year		208		167
Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		165		120
Relating to assets still held at the reporting date		(2)		(8)
Defined Benefit Plan Purchases		69		61
Defined Benefit Plan Sales		14
Settlements	[1]	(12)		(8)
Fair value of net plan assets at end of year		206		165
Equity Security Individually Held [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		2		2
Relating to assets still held at the reporting date		0		0
Defined Benefit Plan Purchases		0		0
Defined Benefit Plan Sales		0
Settlements	[1]	0		0
Fair value of net plan assets at end of year		2		2
Predecessor [Member] | Pepco Holdings LLC [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		2,018		2,236
Fair value of net plan assets at end of year				2,018
Predecessor [Member] | Pepco Holdings LLC [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		348		367
Fair value of net plan assets at end of year				348
Fair Value, Measurements, Recurring [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		3,113		2,765
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	16,613
Fair value of net plan assets at end of year	[2],[3]	19,397		16,613
Fair Value, Measurements, Recurring [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	7,897		6,186
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	14,322
Fair value of net plan assets at end of year	[2]	16,819		14,322
Fair Value, Measurements, Recurring [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	1,444		1,311
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	2,291
Fair value of net plan assets at end of year	[2]	2,578		2,291
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	5,473
Fair value of net plan assets at end of year	[2],[3]	5,313		5,473
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	4,782
Fair value of net plan assets at end of year	[2]	4,477		4,782
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	691
Fair value of net plan assets at end of year	[2]	836		691
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	3,476
Fair value of net plan assets at end of year	[2],[3]	4,535		3,476
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	3,187
Fair value of net plan assets at end of year	[2]	4,237		3,187
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	289
Fair value of net plan assets at end of year	[2]	298		289
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	167
Fair value of net plan assets at end of year	[2],[3]	208		167
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	167
Fair value of net plan assets at end of year	[2]	208		167
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		0	[2]	0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	210
Fair value of net plan assets at end of year	[2]	325		210
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		0		0	[2]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	15
Fair value of net plan assets at end of year	[2]	24		15
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		210
Fair value of net plan assets at end of year		325	[2]	210
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	15
Fair value of net plan assets at end of year		24		15	[2]
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year		0	[2]	0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year		0	[2]	0
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	1,962		1,924
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	1,924
Fair value of net plan assets at end of year	[2]	1,962		1,924
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	445		451
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	451
Fair value of net plan assets at end of year	[2]	445		451
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	991		924
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	924
Fair value of net plan assets at end of year	[2]	991		924
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	828		725
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	725
Fair value of net plan assets at end of year	[2]	828		725
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		117		131	[2]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	131
Fair value of net plan assets at end of year	[2]	117		131
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	748		452
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	4,805
Fair value of net plan assets at end of year	[2]	6,199		4,805
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	131		146
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	599
Fair value of net plan assets at end of year	[2]	692		599
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	1,001
Fair value of net plan assets at end of year	[2]	1,008		1,001
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	166
Fair value of net plan assets at end of year	[2]	265		166
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	3,187
Fair value of net plan assets at end of year	[2]	4,237		3,187
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	287
Fair value of net plan assets at end of year	[2]	296		287
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	165
Fair value of net plan assets at end of year	[2]	206		165
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	833		699
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	699
Fair value of net plan assets at end of year	[2]	833		699
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	107		103
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	103
Fair value of net plan assets at end of year	[2]	107		103
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Private Placement [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		2,535		1,462
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	5,035
Fair value of net plan assets at end of year	[2]	5,681		5,035
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		644		480
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	992
Fair value of net plan assets at end of year	[2]	1,193		992
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		3,571
Fair value of net plan assets at end of year		3,144		3,571
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		510
Fair value of net plan assets at end of year		547		510
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year		0		0
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		2
Fair value of net plan assets at end of year		2		2
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		2
Fair value of net plan assets at end of year		2		2
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year		0		0
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	1,080
Fair value of net plan assets at end of year	[2]	1,200		1,080
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	64
Fair value of net plan assets at end of year	[2]	68		64
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	1,001
Fair value of net plan assets at end of year	[2]	1,008		1,001
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	11
Fair value of net plan assets at end of year	[2]	9		11
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	79
Fair value of net plan assets at end of year	[2]	192		79
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	53
Fair value of net plan assets at end of year	[2]	59		53
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	61
Fair value of net plan assets at end of year	[2]	64		61
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	131
Fair value of net plan assets at end of year	[2]	134		131
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	61
Fair value of net plan assets at end of year	[2]	64		61
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	131
Fair value of net plan assets at end of year	[2]	134		131
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	3,066
Fair value of net plan assets at end of year	[2]	3,847		3,066
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	0		0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	44
Fair value of net plan assets at end of year	[2]	43		44
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	2,901
Fair value of net plan assets at end of year	[2]	3,641		2,901
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	44
Fair value of net plan assets at end of year	[2]	43		44
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	165
Fair value of net plan assets at end of year	[2]	206		165
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		748	[2]	452
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	598
Fair value of net plan assets at end of year	[2]	1,088		598
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure		131		146	[2]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	360
Fair value of net plan assets at end of year	[2]	447		360
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	155
Fair value of net plan assets at end of year		256		155	[2]
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	146
Fair value of net plan assets at end of year	[2]	340		146
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	59
Fair value of net plan assets at end of year		60		59	[2]
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]	0		0
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year		0		0	[2]
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2],[3]			834
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	2,357
Fair value of net plan assets at end of year	[2],[3]			2,357
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			812
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	2,009
Fair value of net plan assets at end of year	[2]			2,009
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			22
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	348
Fair value of net plan assets at end of year	[2]			348
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	825
Fair value of net plan assets at end of year	[2],[3]			825
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	499
Fair value of net plan assets at end of year	[2]			499
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	326
Fair value of net plan assets at end of year	[2]			326
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	698
Fair value of net plan assets at end of year	[2],[3]			698
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	698
Fair value of net plan assets at end of year	[2]			698
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2],[3]	0
Fair value of net plan assets at end of year	[2],[3]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure				0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	50
Fair value of net plan assets at end of year	[2]			50
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure				0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	8
Fair value of net plan assets at end of year	[2]			8
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		50
Fair value of net plan assets at end of year				50
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		8
Fair value of net plan assets at end of year				8
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year				0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year				0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year				0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year		0
Fair value of net plan assets at end of year				0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Private Equity Funds [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			38
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	38
Fair value of net plan assets at end of year	[2]			38
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Real Estate Funds [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			46
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	46
Fair value of net plan assets at end of year	[2]			46
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			504
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	1,316
Fair value of net plan assets at end of year	[2]			1,316
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	114
Fair value of net plan assets at end of year	[2]			114
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	698
Fair value of net plan assets at end of year	[2]			698
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Equity Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure				224
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	559
Fair value of net plan assets at end of year	[2]			559
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Equity Securities [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure				22
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	219
Fair value of net plan assets at end of year	[2]			219
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	129
Fair value of net plan assets at end of year	[2]			129
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	121
Fair value of net plan assets at end of year	[2]			121
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	114
Fair value of net plan assets at end of year	[2]			114
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	121
Fair value of net plan assets at end of year	[2]			121
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	15
Fair value of net plan assets at end of year	[2]			15
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Government Agencies Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	18
Fair value of net plan assets at end of year	[2]			18
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	18
Fair value of net plan assets at end of year	[2]			18
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Corporate Debt Securities [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	625
Fair value of net plan assets at end of year	[2]			625
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	625
Fair value of net plan assets at end of year	[2]			625
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Other Debt Obligations [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Investments, Fair Value Disclosure	[2]			504
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	544
Fair value of net plan assets at end of year	[2]			544
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	0
Fair value of net plan assets at end of year	[2]			0
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	40
Fair value of net plan assets at end of year	[2]			40
Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Pepco Holdings LLC [Member] | Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of net plan assets at beginning of year	[2]	$ 0
Fair value of net plan assets at end of year	[2]			$ 0

[1] ___(a)Represents cash settlemen

[2] ___(a)See Note 12—Fair Value of Financial Assets and Liabilities for a description of levels within the fair value hi

[3] ss.(c)Excludes net liabilities of $28 million and net assets of $27 million at December 31, 2016 and 2015, respectively, which are required to reconcile to the fair value of net plan assets. These items consist primarily of receivables related to pending securities sales, interest and dividends receivable, and payables related to pending securities pur