SEGMENT INFORMATION (Tables)

9 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Financial information of reportable segments

The following tables show summarized financial information related to our reportable segments for the three and nine months ended September 30, 2017 and 2016:

	Utility Operations
(in millions)	Wisconsin		Illinois		Other States			Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Three Months Ended
September 30, 2017
External revenues	$	1,401.3	$	187.2	$	49.8		$	1,638.3	$	—	$	13.6	$	5.6		$	—		$	1,657.5
Intersegment revenues	—		—		—			—		—		111.6		—			(111.6		)	—
Other operation and maintenance	458.3		100.8		21.6			580.7		—		1.5		(1.5		)	(109.0		)	471.7
Depreciation and amortization	131.5		38.9		6.3			176.7		—		18.2		6.3			—			201.2
Operating income (loss)	279.7		12.5		(3.1		)	289.1		—		103.4		1.1			—			393.6
Equity in earnings of transmission affiliate	—		—		—			—		39.2		—		—			—			39.2
Interest expense	48.5		11.0		2.3			61.8		—		16.2		25.4			0.4			103.8

	Utility Operations
(in millions)	Wisconsin		Illinois		Other States			Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Three Months Ended
September 30, 2016
External revenues	$	1,470.6	$	181.8	$	49.9		$	1,702.3	$	—	$	6.2	$	4.0		$	—		$	1,712.5
Intersegment revenues	—		—		—			—		—		105.0		—			(105.0		)	—
Other operation and maintenance	498.2		105.9		21.2			625.3		—		0.4		(3.2		)	(105.0		)	517.5
Depreciation and amortization	124.5		33.5		5.2			163.2		—		17.1		11.3			—			191.6
Operating income (loss)	299.1		11.7		(1.0		)	309.8		—		93.7		(4.5		)	—			399.0
Equity in earnings of transmission affiliate	—		—		—			—		38.3		—		—			—			38.3
Interest expense	44.6		9.3		1.9			55.8		—		15.6		29.7			(2.0		)	99.1

	Utility Operations
(in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Nine Months Ended
September 30, 2017
External revenues	$	4,316.6	$	965.7	$	273.4	$	5,555.7	$	—	$	26.1	$	11.7		$	—		$	5,593.5
Intersegment revenues	—		—		—		—		—		333.2		—			(333.2		)	—
Other operation and maintenance	1,379.9		326.6		73.2		1,779.7		—		4.6		(0.3		)	(330.6		)	1,453.4
Depreciation and amortization	391.1		112.6		18.4		522.1		—		53.1		18.3			—			593.5
Operating income (loss)	835.6		209.3		35.0		1,079.9		—		299.5		(6.3		)	—			1,373.1
Equity in earnings of transmission affiliate	—		—		—		—		122.9		—		—			—			122.9
Interest expense	145.4		33.0		6.5		184.9		—		46.7		81.3			(2.5		)	310.4

	Utility Operations
(in millions)	Wisconsin		Illinois		Other States		Total Utility Operations		Electric Transmission		Non-Utility Energy Infrastructure		Corporate and Other			Reconciling Eliminations			WEC Energy Group Consolidated
Nine Months Ended
September 30, 2016
External revenues	$	4,354.9	$	853.1	$	262.3	$	5,470.3	$	—	$	18.7	$	20.3		$	—		$	5,509.3
Intersegment revenues	0.3		—		—		0.3		—		317.1		—			(317.4		)	—
Other operation and maintenance	1,477.3		340.0		80.6		1,897.9		—		3.5		(13.0		)	(317.4		)	1,571.0
Depreciation and amortization	370.1		99.4		15.5		485.0		—		51.1		33.4			—			569.5
Operating income (loss)	841.3		171.3		33.1		1,045.7		—		281.1		(6.4		)	—			1,320.4
Equity in earnings of transmission affiliate	—		—		—		—		107.7		—		—			—			107.7
Interest expense	133.5		28.8		6.5		168.8		—		46.8		91.2			(6.7		)	300.1