Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2016

Quartertly Financial Data [Abstract]

Quarterly financial data

Quarterly financial information for the years ended December 31, 2016 and 2015 are summarized as follows:

(Millions)	2016								2015
Quarters ended		12/31		9/30		6/30		3/31		12/31		9/30		6/30		3/31
Revenues	$	179	$	180	$	179	$	180	$	180	$	187	$	193	$	195
Pretax income		20		70		65		57		68		45		69		70
Net income	$	29	$	60	$	57	$	51	$	58	$	39	$	49	$	68