Investment in Transmission Affiliates (Tables)

12 Months Ended

Dec. 31, 2020

Equity Method Investments and Joint Ventures [Abstract]

Schedule of changes to our investments in ATC and ATC Holdco

The following tables provide a reconciliation of the changes in our investments in ATC and ATC Holdco:

	2020
(in millions)	ATC		ATC Holdco		Total
Balance at January 1	$	1,684.7	$	36.1	$	1,720.8
Add: Earnings from equity method investment	174.3		1.5		175.8
Add: Capital contributions	21.2		—		21.2
Less: Distributions	146.7		—		146.7
Less: Return of capital	—		6.8		6.8
Balance at December 31	$	1,733.5	$	30.8	$	1,764.3

	2019
(in millions)	ATC		ATC Holdco		Total
Balance at January 1	$	1,625.3	$	40.0	$	1,665.3
Add: Earnings (loss) from equity method investment	132.8		(5.2)		127.6
Add: Capital contributions	51.3		1.3		52.6
Less: Distributions	124.7		—		124.7
Balance at December 31	$	1,684.7	$	36.1	$	1,720.8

	2018
(in millions)	ATC			ATC Holdco		Total
Balance at January 1	$	1,515.8	(1)	$	37.6	$	1,553.4
Add: Earnings (loss) from equity method investment	139.6			(2.9)		136.7
Add: Capital contributions	48.2			5.3		53.5
Less: Distributions	78.2			—		78.2
Less: Other	0.1			—		0.1
Balance at December 31	$	1,625.3		$	40.0	$	1,665.3

(1)    Distributions of $39.9 million, received in the first quarter of 2018, were approved and recorded as a receivable from ATC in other current assets at December 31, 2017.

Schedule of significant related party transactions with ATC

The following table summarizes our significant related party transactions with ATC during the years ended December 31:

(in millions)	2020		2019		2018
Charges to ATC for services and construction	$	27.5	$	25.9	$	21.8
Charges from ATC for network transmission services	350.5		348.1		338.1
Net refund from ATC related to FERC ROE orders	10.7		—		—
Refund from ATC related to a FERC audit	—		—		22.0

Schedule of receivables and payables with ATC

As of December 31, 2020 and 2019, our balance sheets included the following receivables and payables for services provided to or received from ATC:

(in millions)	2020			2019
Accounts receivable for services provided to ATC	$	3.7		$	3.5
Accounts payable for services received from ATC	29.3			29.0
Amounts due from ATC for transmission infrastructure upgrades	4.6		(1)	2.8		(2)

(1)    The transmission infrastructure upgrades were primarily related to WE's and WPS's construction of their new solar projects, Badger Hollow II and Badger Hollow I, respectively.

(2)    The transmission infrastructure upgrades were related to WPS's construction of its two new solar projects, Badger Hollow I and Two Creeks. Amounts due related to Two Creeks were largely reimbursed by ATC in December 2020 as the new generation was placed in service.

Schedule of summarized income statement data for ATC

Summarized financial data for ATC is included in the tables below:

	Year Ended December 31
(in millions)	2020		2019		2018
Income statement data
Operating revenues	$	758.1	$	744.4	$	690.5
Operating expenses	372.5		373.5		358.7
Other expense, net	110.8		110.5		108.3
Net income	$	274.8	$	260.4	$	223.5

Schedule of summarized balance sheet data for ATC

(in millions)	December 31, 2020		December 31, 2019
Balance sheet data
Current assets	$	92.7	$	84.7
Noncurrent assets	5,400.6		5,244.2
Total assets	$	5,493.3	$	5,328.9
Current liabilities	$	310.8	$	502.6
Long-term debt	2,512.2		2,312.8
Other noncurrent liabilities	378.2		298.9
Members' equity	2,292.1		2,214.6
Total liabilities and members' equity	$	5,493.3	$	5,328.9