Debt (Tables)

12 Months Ended

Dec. 31, 2015

Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
December 31
Commercial paper:
Amount outstanding	$159.8	$141.3	$—	$—	$19.9	$—
Weighted average interest rates	0.7%	0.4%	N/A	N/A	0.4%	N/A
Weighted average remaining maturity	4 days	4 days	N/A	N/A	4 days	N/A
Available credit facility capacity	$840.2	$858.7	$300.0	$300.0	$380.1	$400.0



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
For the year ended
Maximum amount outstanding (based on daily outstanding balances)	$181.2	$353.8	$18.4	$38.0	$24.7	$204.7
Average amount outstanding (based on daily outstanding balances)	$119.2	$255.9	$0.2	$0.2	$2.2	$122.9
Weighted average interest rates	0.4%	0.2%	0.4%	0.2%	0.3%	0.1%

Schedule of Debt-To-Capital Ratios

The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:



	Alliant Energy	IPL	WPL
Requirement, not to exceed	65%	58%	58%
Actual	50%	46%	48%

Schedule of Long-term Debt

Long-term debt, net as of December 31 was as follows (dollars in millions):



	2015									2014
	Alliant Energy			IPL			WPL			Alliant Energy			IPL			WPL
Senior Debentures:
5.875%, due 2018		$100.0			$100.0			$—			$100.0			$100.0			$—
7.25%, due 2018	250.0			250.0			—			250.0			250.0			—
3.65%, due 2020	200.0			200.0			—			200.0			200.0			—
3.25%, due 2024	250.0			250.0			—			250.0			250.0			—
3.4%, due 2025 (a)	250.0			250.0			—			—			—			—
5.5%, due 2025	50.0			50.0			—			50.0			50.0			—
6.45%, due 2033	100.0			100.0			—			100.0			100.0			—
6.3%, due 2034	125.0			125.0			—			125.0			125.0			—
6.25%, due 2039	300.0			300.0			—			300.0			300.0			—
4.7%, due 2043	250.0			250.0			—			250.0			250.0			—
3.3% (Retired in 2015)	—			—			—			150.0			150.0			—
	1,875.0			1,875.0			—			1,775.0			1,775.0			—
Debentures:
5%, due 2019	250.0			—			250.0			250.0			—			250.0
4.6%, due 2020	150.0			—			150.0			150.0			—			150.0
2.25%, due 2022	250.0			—			250.0			250.0			—			250.0
6.25%, due 2034	100.0			—			100.0			100.0			—			100.0
6.375%, due 2037	300.0			—			300.0			300.0			—			300.0
7.6%, due 2038	250.0			—			250.0			250.0			—			250.0
4.1%, due 2044	250.0			—			250.0			250.0			—			250.0
	1,550.0			—			1,550.0			1,550.0			—			1,550.0
Pollution Control Revenue Bonds:
5% (Retired in 2015)	—			—			—			16.0			—			16.0
5.375% (Retired in 2015)	—			—			—			14.6			—			14.6
	—			—			—			30.6			—			30.6
Other:
Term loan credit agreement through 2016, 1% at December 31, 2015	250.0			—			—			250.0			—			—
Term loan credit agreement through 2016, 1% at December 31, 2015	60.0			—			—			60.0			—			—
3.45% senior notes, due 2022	75.0			—			—			75.0			—			—
5.06% senior secured notes, due 2016 to 2024	56.8			—			—			58.9			—			—
Other, 1% at December 31, 2015, due 2016 to 2025	3.7			—			—			3.3			—			—
	445.5			—			—			447.2			—			—
Subtotal	3,870.5			1,875.0			1,550.0			3,802.8			1,775.0			1,580.6
Current maturities	(313.4		)	—			—			(183.0		)	(150.0		)	(30.6		)
Unamortized debt issuance costs	(22.3		)	(11.8		)	(9.9		)	(22.4		)	(10.7		)	(10.8		)
Unamortized debt (discount) and premium, net	(12.6		)	(6.3		)	(6.2		)	(13.1		)	(6.3		)	(6.7		)
Long-term debt, net		$3,522.2			$1,856.9			$1,533.9			$3,584.3			$1,608.0			$1,532.5


(a)	In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.

Schedule of Debt Maturities

At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):



	2016		2017		2018		2019		2020
IPL		$—		$—		$350		$—		$200
WPL	—		—		—		250		150
Resources	63		5		6		6		7
Alliant Energy parent company	250		—		—		—		—
Alliant Energy		$313		$5		$356		$256		$357

IPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
December 31
Commercial paper:
Amount outstanding	$159.8	$141.3	$—	$—	$19.9	$—
Weighted average interest rates	0.7%	0.4%	N/A	N/A	0.4%	N/A
Weighted average remaining maturity	4 days	4 days	N/A	N/A	4 days	N/A
Available credit facility capacity	$840.2	$858.7	$300.0	$300.0	$380.1	$400.0



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
For the year ended
Maximum amount outstanding (based on daily outstanding balances)	$181.2	$353.8	$18.4	$38.0	$24.7	$204.7
Average amount outstanding (based on daily outstanding balances)	$119.2	$255.9	$0.2	$0.2	$2.2	$122.9
Weighted average interest rates	0.4%	0.2%	0.4%	0.2%	0.3%	0.1%

Schedule of Debt-To-Capital Ratios

The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:



	Alliant Energy	IPL	WPL
Requirement, not to exceed	65%	58%	58%
Actual	50%	46%	48%

Schedule of Long-term Debt

Long-term debt, net as of December 31 was as follows (dollars in millions):



	2015									2014
	Alliant Energy			IPL			WPL			Alliant Energy			IPL			WPL
Senior Debentures:
5.875%, due 2018		$100.0			$100.0			$—			$100.0			$100.0			$—
7.25%, due 2018	250.0			250.0			—			250.0			250.0			—
3.65%, due 2020	200.0			200.0			—			200.0			200.0			—
3.25%, due 2024	250.0			250.0			—			250.0			250.0			—
3.4%, due 2025 (a)	250.0			250.0			—			—			—			—
5.5%, due 2025	50.0			50.0			—			50.0			50.0			—
6.45%, due 2033	100.0			100.0			—			100.0			100.0			—
6.3%, due 2034	125.0			125.0			—			125.0			125.0			—
6.25%, due 2039	300.0			300.0			—			300.0			300.0			—
4.7%, due 2043	250.0			250.0			—			250.0			250.0			—
3.3% (Retired in 2015)	—			—			—			150.0			150.0			—
	1,875.0			1,875.0			—			1,775.0			1,775.0			—
Debentures:
5%, due 2019	250.0			—			250.0			250.0			—			250.0
4.6%, due 2020	150.0			—			150.0			150.0			—			150.0
2.25%, due 2022	250.0			—			250.0			250.0			—			250.0
6.25%, due 2034	100.0			—			100.0			100.0			—			100.0
6.375%, due 2037	300.0			—			300.0			300.0			—			300.0
7.6%, due 2038	250.0			—			250.0			250.0			—			250.0
4.1%, due 2044	250.0			—			250.0			250.0			—			250.0
	1,550.0			—			1,550.0			1,550.0			—			1,550.0
Pollution Control Revenue Bonds:
5% (Retired in 2015)	—			—			—			16.0			—			16.0
5.375% (Retired in 2015)	—			—			—			14.6			—			14.6
	—			—			—			30.6			—			30.6
Other:
Term loan credit agreement through 2016, 1% at December 31, 2015	250.0			—			—			250.0			—			—
Term loan credit agreement through 2016, 1% at December 31, 2015	60.0			—			—			60.0			—			—
3.45% senior notes, due 2022	75.0			—			—			75.0			—			—
5.06% senior secured notes, due 2016 to 2024	56.8			—			—			58.9			—			—
Other, 1% at December 31, 2015, due 2016 to 2025	3.7			—			—			3.3			—			—
	445.5			—			—			447.2			—			—
Subtotal	3,870.5			1,875.0			1,550.0			3,802.8			1,775.0			1,580.6
Current maturities	(313.4		)	—			—			(183.0		)	(150.0		)	(30.6		)
Unamortized debt issuance costs	(22.3		)	(11.8		)	(9.9		)	(22.4		)	(10.7		)	(10.8		)
Unamortized debt (discount) and premium, net	(12.6		)	(6.3		)	(6.2		)	(13.1		)	(6.3		)	(6.7		)
Long-term debt, net		$3,522.2			$1,856.9			$1,533.9			$3,584.3			$1,608.0			$1,532.5


(a)	In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.

Schedule of Debt Maturities

At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):



	2016		2017		2018		2019		2020
IPL		$—		$—		$350		$—		$200
WPL	—		—		—		250		150
Resources	63		5		6		6		7
Alliant Energy parent company	250		—		—		—		—
Alliant Energy		$313		$5		$356		$256		$357

WPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
December 31
Commercial paper:
Amount outstanding	$159.8	$141.3	$—	$—	$19.9	$—
Weighted average interest rates	0.7%	0.4%	N/A	N/A	0.4%	N/A
Weighted average remaining maturity	4 days	4 days	N/A	N/A	4 days	N/A
Available credit facility capacity	$840.2	$858.7	$300.0	$300.0	$380.1	$400.0



	Alliant Energy		IPL		WPL
	2015	2014	2015	2014	2015	2014
For the year ended
Maximum amount outstanding (based on daily outstanding balances)	$181.2	$353.8	$18.4	$38.0	$24.7	$204.7
Average amount outstanding (based on daily outstanding balances)	$119.2	$255.9	$0.2	$0.2	$2.2	$122.9
Weighted average interest rates	0.4%	0.2%	0.4%	0.2%	0.3%	0.1%

Schedule of Debt-To-Capital Ratios

The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2015 were as follows:



	Alliant Energy	IPL	WPL
Requirement, not to exceed	65%	58%	58%
Actual	50%	46%	48%

Schedule of Long-term Debt

Long-term debt, net as of December 31 was as follows (dollars in millions):



	2015									2014
	Alliant Energy			IPL			WPL			Alliant Energy			IPL			WPL
Senior Debentures:
5.875%, due 2018		$100.0			$100.0			$—			$100.0			$100.0			$—
7.25%, due 2018	250.0			250.0			—			250.0			250.0			—
3.65%, due 2020	200.0			200.0			—			200.0			200.0			—
3.25%, due 2024	250.0			250.0			—			250.0			250.0			—
3.4%, due 2025 (a)	250.0			250.0			—			—			—			—
5.5%, due 2025	50.0			50.0			—			50.0			50.0			—
6.45%, due 2033	100.0			100.0			—			100.0			100.0			—
6.3%, due 2034	125.0			125.0			—			125.0			125.0			—
6.25%, due 2039	300.0			300.0			—			300.0			300.0			—
4.7%, due 2043	250.0			250.0			—			250.0			250.0			—
3.3% (Retired in 2015)	—			—			—			150.0			150.0			—
	1,875.0			1,875.0			—			1,775.0			1,775.0			—
Debentures:
5%, due 2019	250.0			—			250.0			250.0			—			250.0
4.6%, due 2020	150.0			—			150.0			150.0			—			150.0
2.25%, due 2022	250.0			—			250.0			250.0			—			250.0
6.25%, due 2034	100.0			—			100.0			100.0			—			100.0
6.375%, due 2037	300.0			—			300.0			300.0			—			300.0
7.6%, due 2038	250.0			—			250.0			250.0			—			250.0
4.1%, due 2044	250.0			—			250.0			250.0			—			250.0
	1,550.0			—			1,550.0			1,550.0			—			1,550.0
Pollution Control Revenue Bonds:
5% (Retired in 2015)	—			—			—			16.0			—			16.0
5.375% (Retired in 2015)	—			—			—			14.6			—			14.6
	—			—			—			30.6			—			30.6
Other:
Term loan credit agreement through 2016, 1% at December 31, 2015	250.0			—			—			250.0			—			—
Term loan credit agreement through 2016, 1% at December 31, 2015	60.0			—			—			60.0			—			—
3.45% senior notes, due 2022	75.0			—			—			75.0			—			—
5.06% senior secured notes, due 2016 to 2024	56.8			—			—			58.9			—			—
Other, 1% at December 31, 2015, due 2016 to 2025	3.7			—			—			3.3			—			—
	445.5			—			—			447.2			—			—
Subtotal	3,870.5			1,875.0			1,550.0			3,802.8			1,775.0			1,580.6
Current maturities	(313.4		)	—			—			(183.0		)	(150.0		)	(30.6		)
Unamortized debt issuance costs	(22.3		)	(11.8		)	(9.9		)	(22.4		)	(10.7		)	(10.8		)
Unamortized debt (discount) and premium, net	(12.6		)	(6.3		)	(6.2		)	(13.1		)	(6.3		)	(6.7		)
Long-term debt, net		$3,522.2			$1,856.9			$1,533.9			$3,584.3			$1,608.0			$1,532.5


(a)	In 2015, IPL issued $250.0 million of 3.4% senior debentures due 2025. The proceeds from the issuance were used by IPL to reduce commercial paper classified as long-term debt by $111 million, reduce cash amounts received from its sales of accounts receivable program and for general corporate purposes.

Schedule of Debt Maturities

At December 31, 2015, debt maturities for 2016 through 2020 were as follows (in millions):



	2016		2017		2018		2019		2020
IPL		$—		$—		$350		$—		$200
WPL	—		—		—		250		150
Resources	63		5		6		6		7
Alliant Energy parent company	250		—		—		—		—
Alliant Energy		$313		$5		$356		$256		$357

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details