Segment Information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule of information concerning our reportable segments

The following tables show summarized financial information related to our reportable segments for the years ended December 31, 2019, 2018, and 2017.

	Utility Operations
2019 (in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
External revenues	$	5,647.1	$	1,357.1	$	426.0	$	7,430.2	$	—	$	88.5	$	4.4		$	—		$	7,523.1
Intersegment revenues	—		—		—		—		—		407.4		—			(407.4		)	—
Other operation and maintenance	1,591.3		461.1		98.5		2,150.9		—		19.7		14.0			0.2			2,184.8
Depreciation and amortization	617.0		181.3		27.5		825.8		—		92.0		24.3			(15.8		)	926.3
Operating income (loss)	1,189.6		291.9		65.3		1,546.8		—		366.6		(34.4		)	(347.6		)	1,531.4
Equity in earnings of transmission affiliates	—		—		—		—		127.6		—		—			—			127.6
Interest expense	572.0		59.0		8.5		639.5		13.1		62.1		140.9			(354.1		)	501.5
Capital   expenditures and asset acquisitions	1,378.6		624.9		109.1		2,112.6		—		389.9		26.5			—			2,529.0
Total assets *	23,934.8		6,932.5		1,237.8		32,105.1		1,723.1		3,654.1		814.0			(3,344.5		)	34,951.8

* Total assets at December 31, 2019 reflect an elimination of $1,896.7 million for all lease activity between We Power and WE.

	Utility Operations
2018 (in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
External revenues	$	5,794.7	$	1,400.0	$	438.2	$	7,632.9	$	—	$	37.9	$	8.7		$	—		$	7,679.5
Intersegment revenues	—		—		—		—		—		430.5		—			(430.5		)	—
Other operation and maintenance	2,076.1		472.3		101.0		2,649.4		—		12.6		1.8			(393.3		)	2,270.5
Depreciation and amortization	546.6		170.3		24.1		741.0		—		75.7		29.1			—			845.8
Operating income (loss)	800.2		255.8		68.8		1,124.8		—		365.8		(22.2		)	—			1,468.4
Equity in earnings of transmission affiliates	—		—		—		—		136.7		—		—			—			136.7
Interest expense	200.7		51.2		8.7		260.6		0.3		63.7		125.8			(5.3		)	445.1
Capital   expenditures and asset acquisitions	1,466.1		547.1		103.6		2,116.8		—		260.6		39.7			—			2,417.1
Total assets *	23,407.0		6,483.3		1,147.9		31,038.2		1,665.3		3,227.2		959.6			(3,414.5		)	33,475.8

* Total assets at December 31, 2018 reflect an elimination of $1,968.5 million for all lease activity between We Power and WE.

	Utility Operations
2017 (in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
External revenues	$	5,829.2	$	1,355.5	$	411.2	$	7,595.9	$	—	$	38.9	$	13.7		$	—		$	7,648.5
Intersegment revenues	—		—		—		—		—		446.3		—			(446.3		)	—
Other operation and maintenance	1,923.2		464.2		101.1		2,488.5		—		7.3		1.4			(441.1		)	2,056.1
Depreciation and amortization	523.9		152.6		24.8		701.3		—		71.4		25.9			—			798.6
Operating income (loss)	1,055.2		279.9		54.4		1,389.5		—		400.5		(13.9		)	—			1,776.1
Equity in earnings of transmission affiliates	—		—		—		—		154.3		—		—			—			154.3
Interest expense	193.7		45.0		8.7		247.4		—		62.8		107.3			(1.8		)	415.7
Capital   expenditures	1,152.3		545.2		74.5		1,772.0		—		35.4		152.1			—			1,959.5
Total assets *	22,237.1		6,144.7		1,067.8		29,449.6		1,593.4		2,992.8		953.6			(3,398.9		)	31,590.5

* Total assets at December 31, 2017 reflect an elimination of $2,038.1 million for all lease activity between We Power and WE.