Property Plant and Equipment Property Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Public Utility Property, Plant, and Equipment

Major classes of property, plant and equipment:

(Millions of Dollars)	Dec. 31, 2018			Dec. 31, 2017
Property, plant and equipment
Electric plant	$	7,227.7		$	6,765.3
CWIP	847.3			351.9
Total property, plant and equipment	8,075.0			7,117.2
Less accumulated depreciation	(2,128.6		)	(2,021.6		)
	$	5,946.4		$	5,095.6