Condensed Statements of Consolidated Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Statements Of Consolidated Comprehensive Income [Abstract]
Net income	$ 98	$ 94	$ 196	$ 197
Other comprehensive income (loss):
Cash flow hedges - derivative value net loss recognized in net income (net of tax expense of $-, $-, $- and $-) (Note 1)	1	1	1	1
Defined benefit pension plans (net of tax benefit of $-, $-, $- and $-) (Note 9)			1
Total other comprehensive income (loss)	1	1	2	1
Comprehensive income	$ 99	$ 95	$ 198	$ 198