XML 45 R12.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Receivables | 12 Months Ended
--- | ---
Dec. 31, 2018
Accounts Receivable [Line Items] |
Receivables | RECEIVABLES (a) Accounts Receivable - Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Customer |  | $91.0 |  |  |  | $103.3 |  |  |  | $— |  |  |  | $— |  |  |  | $84.8 |  |  |  | $97.7 |
Unbilled utility revenues | 74.2 |  |  | 85.1 |  |  | — |  |  | — |  |  | 74.2 |  |  | 85.1 |
Deferred proceeds | 119.4 |  |  | 222.1 |  |  | 119.4 |  |  | 222.1 |  |  | — |  |  | — |
Other | 76.3 |  |  | 84.3 |  |  | 37.2 |  |  | 44.1 |  |  | 38.5 |  |  | 40.1 |
Allowance for doubtful accounts | (10.5 | ) |  | (12.0 | ) |  | (3.1 | ) |  | (1.3 | ) |  | (7.4 | ) |  | (10.7 | )
|  | $350.4 |  |  |  | $482.8 |  |  |  | $153.5 |  |  |  | $264.9 |  |  |  | $190.1 |  |  |  | $212.2 |
(b) Sales of Accounts Receivable - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2018, IPL amended and extended through March 2021 the purchase commitment from the third party to which it sells its receivables. IPL pays a monthly fee to the third party that varies based on interest rates, limits on cash proceeds and cash amounts received from the third party. Deferred proceeds represent IPL’s interest in the receivables sold to the third party. At IPL’s request, deferred proceeds are paid to IPL from collections of receivables, after paying any required expenses incurred by the third party and the collection agent. Corporate Services acts as collection agent for the third party and receives a fee for collection services. The Receivables Agreement can be terminated by the third party if arrears or write-offs exceed certain levels. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. IPL believes that the allowance for doubtful accounts related to its sales of receivables is a reasonable approximation of credit risk of the customers that generated the receivables. Refer to Note 16 for discussion of the fair value of deferred proceeds. Under the Receivables Agreement, IPL has the right to receive cash proceeds, up to a certain limit, from the third party in exchange for the receivables sold. Effective April 2018, the limit on cash proceeds fluctuates between $90 million and $110 million. Cash proceeds are used by IPL to meet short-term financing needs, and cannot exceed the current limit or amount of receivables available for sale, whichever is less. As of December 31, 2018, IPL had no available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program were as follows (in millions):
| Maximum |  | Average
| 2018 |  | 2017 |  | 2016 |  | 2018 |  | 2017 |  | 2016
Outstanding aggregate cash proceeds | $116.0 |  | $112.0 |  | $172.0 |  | $53.4 |  | $62.2 |  | $73.2
As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2018 |  | 2017
Customer accounts receivable | $140.1 |  | $133.8
Unbilled utility revenues | 97.1 |  | 112.7
Other receivables | 0.1 |  | 0.3
Receivables sold to third party | 237.3 |  | 246.8
Less: cash proceeds | 108.0 |  | 12.0
Deferred proceeds | 129.3 |  | 234.8
Less: allowance for doubtful accounts | 9.9 |  | 12.7
Fair value of deferred proceeds | $119.4 |  | $222.1
Outstanding receivables past due | $35.5 |  | $44.7
Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2018 |  | 2017 |  | 2016
Collections | $2,076.7 |  | $1,647.1 |  | $1,818.1
Write-offs, net of recoveries | 21.3 |  | 17.7 |  | 4.8
In connection with the implementation of IPL’s new customer billing and information system in 2016, IPL postponed the write-off of customer bills for a portion of 2016, resulting in lower write-offs in 2016 compared to 2017 and 2018.
IPL [Member] |
Accounts Receivable [Line Items] |
Receivables | RECEIVABLES (a) Accounts Receivable - Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Customer |  | $91.0 |  |  |  | $103.3 |  |  |  | $— |  |  |  | $— |  |  |  | $84.8 |  |  |  | $97.7 |
Unbilled utility revenues | 74.2 |  |  | 85.1 |  |  | — |  |  | — |  |  | 74.2 |  |  | 85.1 |
Deferred proceeds | 119.4 |  |  | 222.1 |  |  | 119.4 |  |  | 222.1 |  |  | — |  |  | — |
Other | 76.3 |  |  | 84.3 |  |  | 37.2 |  |  | 44.1 |  |  | 38.5 |  |  | 40.1 |
Allowance for doubtful accounts | (10.5 | ) |  | (12.0 | ) |  | (3.1 | ) |  | (1.3 | ) |  | (7.4 | ) |  | (10.7 | )
|  | $350.4 |  |  |  | $482.8 |  |  |  | $153.5 |  |  |  | $264.9 |  |  |  | $190.1 |  |  |  | $212.2 |
(b) Sales of Accounts Receivable - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. In March 2018, IPL amended and extended through March 2021 the purchase commitment from the third party to which it sells its receivables. IPL pays a monthly fee to the third party that varies based on interest rates, limits on cash proceeds and cash amounts received from the third party. Deferred proceeds represent IPL’s interest in the receivables sold to the third party. At IPL’s request, deferred proceeds are paid to IPL from collections of receivables, after paying any required expenses incurred by the third party and the collection agent. Corporate Services acts as collection agent for the third party and receives a fee for collection services. The Receivables Agreement can be terminated by the third party if arrears or write-offs exceed certain levels. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. IPL believes that the allowance for doubtful accounts related to its sales of receivables is a reasonable approximation of credit risk of the customers that generated the receivables. Refer to Note 16 for discussion of the fair value of deferred proceeds. Under the Receivables Agreement, IPL has the right to receive cash proceeds, up to a certain limit, from the third party in exchange for the receivables sold. Effective April 2018, the limit on cash proceeds fluctuates between $90 million and $110 million. Cash proceeds are used by IPL to meet short-term financing needs, and cannot exceed the current limit or amount of receivables available for sale, whichever is less. As of December 31, 2018, IPL had no available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program were as follows (in millions):
| Maximum |  | Average
| 2018 |  | 2017 |  | 2016 |  | 2018 |  | 2017 |  | 2016
Outstanding aggregate cash proceeds | $116.0 |  | $112.0 |  | $172.0 |  | $53.4 |  | $62.2 |  | $73.2
As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2018 |  | 2017
Customer accounts receivable | $140.1 |  | $133.8
Unbilled utility revenues | 97.1 |  | 112.7
Other receivables | 0.1 |  | 0.3
Receivables sold to third party | 237.3 |  | 246.8
Less: cash proceeds | 108.0 |  | 12.0
Deferred proceeds | 129.3 |  | 234.8
Less: allowance for doubtful accounts | 9.9 |  | 12.7
Fair value of deferred proceeds | $119.4 |  | $222.1
Outstanding receivables past due | $35.5 |  | $44.7
Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):
| 2018 |  | 2017 |  | 2016
Collections | $2,076.7 |  | $1,647.1 |  | $1,818.1
Write-offs, net of recoveries | 21.3 |  | 17.7 |  | 4.8
In connection with the implementation of IPL’s new customer billing and information system in 2016, IPL postponed the write-off of customer bills for a portion of 2016, resulting in lower write-offs in 2016 compared to 2017 and 2018.
WPL [Member] |
Accounts Receivable [Line Items] |
Receivables | RECEIVABLES (a) Accounts Receivable - Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Customer |  | $91.0 |  |  |  | $103.3 |  |  |  | $— |  |  |  | $— |  |  |  | $84.8 |  |  |  | $97.7 |
Unbilled utility revenues | 74.2 |  |  | 85.1 |  |  | — |  |  | — |  |  | 74.2 |  |  | 85.1 |
Deferred proceeds | 119.4 |  |  | 222.1 |  |  | 119.4 |  |  | 222.1 |  |  | — |  |  | — |
Other | 76.3 |  |  | 84.3 |  |  | 37.2 |  |  | 44.1 |  |  | 38.5 |  |  | 40.1 |
Allowance for doubtful accounts | (10.5 | ) |  | (12.0 | ) |  | (3.1 | ) |  | (1.3 | ) |  | (7.4 | ) |  | (10.7 | )
|  | $350.4 |  |  |  | $482.8 |  |  |  | $153.5 |  |  |  | $264.9 |  |  |  | $190.1 |  |  |  | $212.2 |

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5066-111524 Reference 2: 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(4)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(6)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 4: 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(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5162-111524 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(5)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 + Details
Name: | us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |