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Asset Retirement Obligations (AROs) | 12 Months Ended
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Dec. 31, 2012
Schedule of Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS (AROs) AROs recognized by Alliant Energy, IPL and WPL relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind projects, certain ash ponds, certain coal yards, active ash landfills and above ground storage tanks. Alliant Energy’s, IPL’s and WPL’s recognized AROs also include legal obligations for the management and final disposition of asbestos and PCB. Alliant Energy’s, IPL’s and WPL’s AROs are recorded in “Other long-term liabilities and deferred credits” on the Consolidated Balance Sheets. Refer to Note 1(b) for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011 |  | 2012 |  | 2011
Balance, January 1 |  | $91.1 |  |  |  | $75.9 |  |  |  | $56.2 |  |  |  | $43.6 |  |  |  | $34.9 |  |  |  | $32.3 |
Revisions in estimated cash flows (a) | (6.4 | ) |  | 7.8 |  |  | (9.2 | ) |  | 7.7 |  |  | 2.8 |  |  | 0.1 |
Liabilities settled | (3.4 | ) |  | (0.9 | ) |  | (3.3 | ) |  | (0.8 | ) |  | (0.1 | ) |  | (0.1 | )
Liabilities incurred (b) | 16.8 |  |  | 4.0 |  |  | — |  |  | 3.1 |  |  | 7.7 |  |  | 0.9 |
Accretion expense | 3.4 |  |  | 4.3 |  |  | 1.8 |  |  | 2.6 |  |  | 1.6 |  |  | 1.7 |
Balance, December 31 |  | $101.5 |  |  |  | $91.1 |  |  |  | $45.5 |  |  |  | $56.2 |  |  |  | $46.9 |  |  |  | $34.9 |
(a) | In 2012 and 2011, IPL recorded revisions in estimated cash flows of ($8.2) million and $7.0 million, respectively, based on revised remediation timing and cost information for asbestos remediation at Sixth Street.
(b) | In 2012, Resources recorded AROs of $9.1 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.
In addition, certain of Alliant Energy’s, IPL’s and WPL’s AROs related to electric generating facility assets have not been recognized. Due to an indeterminate remediation date, the fair values of the AROs for these assets cannot be currently estimated. A liability for these AROs will be recorded when fair value is determinable. Removal costs of these facilities are being recovered in rates and are recorded in regulatory liabilities.
IPL [Member] |
Schedule of Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS (AROs) AROs recognized by Alliant Energy, IPL and WPL relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind projects, certain ash ponds, certain coal yards, active ash landfills and above ground storage tanks. Alliant Energy’s, IPL’s and WPL’s recognized AROs also include legal obligations for the management and final disposition of asbestos and PCB. Alliant Energy’s, IPL’s and WPL’s AROs are recorded in “Other long-term liabilities and deferred credits” on the Consolidated Balance Sheets. Refer to Note 1(b) for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011 |  | 2012 |  | 2011
Balance, January 1 |  | $91.1 |  |  |  | $75.9 |  |  |  | $56.2 |  |  |  | $43.6 |  |  |  | $34.9 |  |  |  | $32.3 |
Revisions in estimated cash flows (a) | (6.4 | ) |  | 7.8 |  |  | (9.2 | ) |  | 7.7 |  |  | 2.8 |  |  | 0.1 |
Liabilities settled | (3.4 | ) |  | (0.9 | ) |  | (3.3 | ) |  | (0.8 | ) |  | (0.1 | ) |  | (0.1 | )
Liabilities incurred (b) | 16.8 |  |  | 4.0 |  |  | — |  |  | 3.1 |  |  | 7.7 |  |  | 0.9 |
Accretion expense | 3.4 |  |  | 4.3 |  |  | 1.8 |  |  | 2.6 |  |  | 1.6 |  |  | 1.7 |
Balance, December 31 |  | $101.5 |  |  |  | $91.1 |  |  |  | $45.5 |  |  |  | $56.2 |  |  |  | $46.9 |  |  |  | $34.9 |
(a) | In 2012 and 2011, IPL recorded revisions in estimated cash flows of ($8.2) million and $7.0 million, respectively, based on revised remediation timing and cost information for asbestos remediation at Sixth Street.
(b) | In 2012, Resources recorded AROs of $9.1 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.
In addition, certain of Alliant Energy’s, IPL’s and WPL’s AROs related to electric generating facility assets have not been recognized. Due to an indeterminate remediation date, the fair values of the AROs for these assets cannot be currently estimated. A liability for these AROs will be recorded when fair value is determinable. Removal costs of these facilities are being recovered in rates and are recorded in regulatory liabilities.
WPL [Member] |
Schedule of Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS (AROs) AROs recognized by Alliant Energy, IPL and WPL relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind projects, certain ash ponds, certain coal yards, active ash landfills and above ground storage tanks. Alliant Energy’s, IPL’s and WPL’s recognized AROs also include legal obligations for the management and final disposition of asbestos and PCB. Alliant Energy’s, IPL’s and WPL’s AROs are recorded in “Other long-term liabilities and deferred credits” on the Consolidated Balance Sheets. Refer to Note 1(b) for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011 |  | 2012 |  | 2011
Balance, January 1 |  | $91.1 |  |  |  | $75.9 |  |  |  | $56.2 |  |  |  | $43.6 |  |  |  | $34.9 |  |  |  | $32.3 |
Revisions in estimated cash flows (a) | (6.4 | ) |  | 7.8 |  |  | (9.2 | ) |  | 7.7 |  |  | 2.8 |  |  | 0.1 |
Liabilities settled | (3.4 | ) |  | (0.9 | ) |  | (3.3 | ) |  | (0.8 | ) |  | (0.1 | ) |  | (0.1 | )
Liabilities incurred (b) | 16.8 |  |  | 4.0 |  |  | — |  |  | 3.1 |  |  | 7.7 |  |  | 0.9 |
Accretion expense | 3.4 |  |  | 4.3 |  |  | 1.8 |  |  | 2.6 |  |  | 1.6 |  |  | 1.7 |
Balance, December 31 |  | $101.5 |  |  |  | $91.1 |  |  |  | $45.5 |  |  |  | $56.2 |  |  |  | $46.9 |  |  |  | $34.9 |
(a) | In 2012 and 2011, IPL recorded revisions in estimated cash flows of ($8.2) million and $7.0 million, respectively, based on revised remediation timing and cost information for asbestos remediation at Sixth Street.
(b) | In 2012, Resources recorded AROs of $9.1 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.
In addition, certain of Alliant Energy’s, IPL’s and WPL’s AROs related to electric generating facility assets have not been recognized. Due to an indeterminate remediation date, the fair values of the AROs for these assets cannot be currently estimated. A liability for these AROs will be recorded when fair value is determinable. Removal costs of these facilities are being recovered in rates and are recorded in regulatory liabilities.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7569-110849 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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