QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

Accordingly, comparisons among quarters of a year may not represent overall trends and changes in operations.

	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
(in millions)	2016
Operating Revenue	$	243		$	317	$	394	$	281
Operating Income	12			72		122		37
Net Income (Loss)	(1		)	41		72		12
	2015
Operating Revenue	$	273		$	340	$	409	$	284
Operating Income	28			74		120		36
Net Income	9			38		69		12