Regulatory Matters (Tables)

6 Months Ended

Jun. 30, 2021

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$914	$890	$865	$843	$49	$47
Pension and OPEB costs	559	580	281	291	278	289
Asset retirement obligations	123	119	85	81	38	38
Assets retired early	103	113	72	77	31	36
IPL’s DAEC PPA amendment	102	110	102	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	54	55	—	—	54	55
Derivatives	3	26	2	13	1	13
Other	137	117	81	68	56	49
	$1,995	$2,010	$1,488	$1,483	$507	$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$661	$732	$322	$331	$339	$401
Cost of removal obligations	373	367	245	238	128	129
Derivatives	81	28	40	25	41	3
Electric transmission cost recovery	48	68	23	39	25	29
WPL’s West Riverside liquidated damages	40	38	—	—	40	38
Other	51	73	17	43	34	30
	$1,254	$1,306	$647	$676	$607	$630

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$914	$890	$865	$843	$49	$47
Pension and OPEB costs	559	580	281	291	278	289
Asset retirement obligations	123	119	85	81	38	38
Assets retired early	103	113	72	77	31	36
IPL’s DAEC PPA amendment	102	110	102	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	54	55	—	—	54	55
Derivatives	3	26	2	13	1	13
Other	137	117	81	68	56	49
	$1,995	$2,010	$1,488	$1,483	$507	$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$661	$732	$322	$331	$339	$401
Cost of removal obligations	373	367	245	238	128	129
Derivatives	81	28	40	25	41	3
Electric transmission cost recovery	48	68	23	39	25	29
WPL’s West Riverside liquidated damages	40	38	—	—	40	38
Other	51	73	17	43	34	30
	$1,254	$1,306	$647	$676	$607	$630

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$914	$890	$865	$843	$49	$47
Pension and OPEB costs	559	580	281	291	278	289
Asset retirement obligations	123	119	85	81	38	38
Assets retired early	103	113	72	77	31	36
IPL’s DAEC PPA amendment	102	110	102	110	—	—
WPL’s Western Wisconsin gas distribution expansion investments	54	55	—	—	54	55
Derivatives	3	26	2	13	1	13
Other	137	117	81	68	56	49
	$1,995	$2,010	$1,488	$1,483	$507	$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020	June 30, 2021	December 31, 2020
Tax-related	$661	$732	$322	$331	$339	$401
Cost of removal obligations	373	367	245	238	128	129
Derivatives	81	28	40	25	41	3
Electric transmission cost recovery	48	68	23	39	25	29
WPL’s West Riverside liquidated damages	40	38	—	—	40	38
Other	51	73	17	43	34	30
	$1,254	$1,306	$647	$676	$607	$630