Financing Receivables (Schedule Of Assets Under Lease Receivables) (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) MW
Powerton Station Units 5 And 6 [Member]
Schedule of Financial Receivables [Line Items]
Location	IL
Gross Investment | $	$ 134
% Owned	64.00%
Total MW | MW	1,538
Fuel Type	Coal
Counterparties’ S&P Credit Ratings	BB-
Counterparty	NRG Energy, Inc.
Joliet Station Units 7 And 8 [Member]
Schedule of Financial Receivables [Line Items]
Location	IL
Gross Investment | $	$ 83
% Owned	64.00%
Total MW | MW	1,044
Fuel Type	Gas
Counterparties’ S&P Credit Ratings	BB-
Counterparty	NRG Energy, Inc.
Keystone Station Units 1 And 2 [Member]
Schedule of Financial Receivables [Line Items]
Location	PA
Gross Investment | $	$ 55
% Owned	17.00%
Total MW | MW	1,711
Fuel Type	Coal
Counterparties’ S&P Credit Ratings	CCC (B)	[1]
Counterparty	REMA
Conemaugh Station Units 1 And 2 [Member]
Schedule of Financial Receivables [Line Items]
Location	PA
Gross Investment | $	$ 55
% Owned	17.00%
Total MW | MW	1,711
Fuel Type	Coal
Counterparties’ S&P Credit Ratings	CCC (B)	[1]
Counterparty	REMA
Shawville Station Units 1, 2, 3 And 4 [Member]
Schedule of Financial Receivables [Line Items]
Location	PA
Gross Investment | $	$ 109
% Owned	100.00%
Total MW | MW	603
Fuel Type	Coal (A)	[2]
Counterparties’ S&P Credit Ratings	CCC (B)	[1]
Counterparty	REMA

[1] On May 24, 2016, S&P lowered its corporate credit rating on REMA’s parent company, GenOn Energy Inc. (GenOn) and affiliates (including REMA) to “CCC” from “CCC+” due to a weaker forward power curve, milder weather patterns and weakening financial measures. On October 7, 2016, Moody’s downgraded the GenOn Corporate Family Rating to Caa3 to reflect its high debt burden relative to cash flow. GenOn reported in August 2016 that it did not expect to have sufficient liquidity to repay the senior unsecured notes due in June 2017.

[2] REMA notified PJM that it deactivated the coal-fired units at the Shawville generating facility in June 2015 and has disclosed that it expects to return the Shawville units to service in the late fall of 2016 with the ability to use natural gas.