Quarterly financial data (unaudited):

12 Months Ended

Dec. 31, 2018

Quarterly financial data (unaudited):

13. Quarterly financial data (unaudited):

Summarized quarterly financial information for 2018 and 2017 is as follows:


	First		Second		Third		Fourth
	Quarter		Quarter		Quarter		Quarter
	(dollars in thousands)
2018
Operating revenues	$	373,646	$	365,921	$	384,644	$	355,902
Operating margin		69,931		60,849		54,845		39,351
Net margin		27,400		17,285		11,334		(4,820)

2017
Operating revenues	$	354,170	$	361,369	$	376,656	$	342,001
Operating margin		69,330		63,472		59,520		46,548
Net margin		21,454		15,676		11,555		2,592

The negative net margins in the fourth quarter of 2018 were due to reductions to revenue requirements in order to achieve, but not exceed, the targeted margins for interest ratio of 1.14.