Unaudited Quarterly Information

12 Months Ended

Dec. 31, 2016

Unaudited Quarterly Information [Abstract]

Unaudited Quarterly Information [Text Block]

Unaudited Quarterly Information

Summarized quarterly financial data is as follows:

	Year Ended December 31, 2016
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	656	$	763	$	909	$	731
Operating income	79		158		258		132
Net income	17		71		136		52

	Year Ended December 31, 2015
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in millions)
Revenues	$	617	$	705	$	827	$	697
Operating income	101		158		244		105
Net income	31		69		124		37