Revenues (Tables)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

In the following tables, regulated electric revenue is classified by the type of goods/services rendered and market/customer type.

	Three Months Ended
(Thousands of Dollars)	June 30, 2018		June 30, 2017
Major product lines
Revenue from contracts with customers:
Residential	$	85,107	$	84,188
Commercial and industrial (C&I)	200,760		215,805
Other	11,363		12,242
Total retail	297,230		312,235
Wholesale	115,629		101,893
Transmission	58,970		56,394
Other	2,858		2,065
Total revenue from contracts with customers	474,687		472,587
Alternative revenue and other	6,651		7,209
Total revenues	$	481,338	$	479,796

	Six Months Ended
(Thousands of Dollars)	June 30, 2018		June 30, 2017
Major product lines
Revenue from contracts with customers:
Residential	$	165,156	$	163,789
C&I	396,531		416,762
Other	21,027		21,854
Total retail	582,714		602,405
Wholesale	208,861		193,034
Transmission	114,616		110,572
Other	10,389		4,010
Total revenue from contracts with customers	916,580		910,021
Alternative revenue and other	11,990		29,847
Total revenues	$	928,570	$	939,868