Unaudited Quarterly Data (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Data [Abstract]

Schedule Of Unaudited Quarterly Data

Presented in the tables below are supplemental, unaudited, consolidated, quarterly financial data for each of the four quarters in the years ended December 31, 2019 and 2018, respectively. The operating results for any quarter are not indicative of results that may be expected for a full year or any future periods.

	2019
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
Operating revenues	$	813	$	882	$	1,013	$	902
Operating income	238		302		406		224
Net income attributable to common shareholders	113		170		240		98
Basic earnings per share: (a)
Net income attributable to common shareholders	$	0.62	$	0.94	$	1.33	$	0.54
Diluted earnings per share:
Net income attributable to common shareholders	0.62		0.94		1.33		0.54

(a) Amounts may not sum due to rounding.

	2018
	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
Operating revenues	$	761	$	853	$	976	$	850
Operating income	217		302		335		248
Net income attributable to common shareholders	106		162		187		112
Basic earnings per share:
Net income attributable to common shareholders	$	0.60	$	0.90	$	1.04	$	0.62
Diluted earnings per share: (a)
Net income attributable to common shareholders	0.59		0.91		1.04		0.62

(a)

Amounts may not sum due to rounding.