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Asset Retirement Obligations | 9 Months Ended
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Sep. 30, 2014
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Balance, January 1 |  | $109.7 |  |  |  | $101.5 |  |  |  | $47.9 |  |  |  | $45.5 |  |  |  | $52.4 |  |  |  | $46.9 |
Revisions in estimated cash flows | — |  |  | 3.4 |  |  | — |  |  | 0.8 |  |  | — |  |  | 2.6 |
Liabilities settled | (1.0 | ) |  | (0.9 | ) |  | (0.5 | ) |  | (0.1 | ) |  | (0.5 | ) |  | (0.8 | )
Liabilities incurred (a) | 16.5 |  |  | — |  |  | 16.3 |  |  | — |  |  | 0.2 |  |  | — |
Accretion expense | 3.3 |  |  | 2.8 |  |  | 1.6 |  |  | 1.3 |  |  | 1.3 |  |  | 1.2 |
Balance, September 30 |  | $128.5 |  |  |  | $106.8 |  |  |  | $65.3 |  |  |  | $47.5 |  |  |  | $53.4 |  |  |  | $49.9 |
(a) | In 2014, IPL recorded AROs of $12.0 million related to its Sutherland Generating Station.
IPL [Member] |
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Balance, January 1 |  | $109.7 |  |  |  | $101.5 |  |  |  | $47.9 |  |  |  | $45.5 |  |  |  | $52.4 |  |  |  | $46.9 |
Revisions in estimated cash flows | — |  |  | 3.4 |  |  | — |  |  | 0.8 |  |  | — |  |  | 2.6 |
Liabilities settled | (1.0 | ) |  | (0.9 | ) |  | (0.5 | ) |  | (0.1 | ) |  | (0.5 | ) |  | (0.8 | )
Liabilities incurred (a) | 16.5 |  |  | — |  |  | 16.3 |  |  | — |  |  | 0.2 |  |  | — |
Accretion expense | 3.3 |  |  | 2.8 |  |  | 1.6 |  |  | 1.3 |  |  | 1.3 |  |  | 1.2 |
Balance, September 30 |  | $128.5 |  |  |  | $106.8 |  |  |  | $65.3 |  |  |  | $47.5 |  |  |  | $53.4 |  |  |  | $49.9 |
(a) | In 2014, IPL recorded AROs of $12.0 million related to its Sutherland Generating Station.
WPL [Member] |
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations (AROs) | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2014 |  | 2013 |  | 2014 |  | 2013 |  | 2014 |  | 2013
Balance, January 1 |  | $109.7 |  |  |  | $101.5 |  |  |  | $47.9 |  |  |  | $45.5 |  |  |  | $52.4 |  |  |  | $46.9 |
Revisions in estimated cash flows | — |  |  | 3.4 |  |  | — |  |  | 0.8 |  |  | — |  |  | 2.6 |
Liabilities settled | (1.0 | ) |  | (0.9 | ) |  | (0.5 | ) |  | (0.1 | ) |  | (0.5 | ) |  | (0.8 | )
Liabilities incurred (a) | 16.5 |  |  | — |  |  | 16.3 |  |  | — |  |  | 0.2 |  |  | — |
Accretion expense | 3.3 |  |  | 2.8 |  |  | 1.6 |  |  | 1.3 |  |  | 1.3 |  |  | 1.2 |
Balance, September 30 |  | $128.5 |  |  |  | $106.8 |  |  |  | $65.3 |  |  |  | $47.5 |  |  |  | $53.4 |  |  |  | $49.9 |
(a) | In 2014, IPL recorded AROs of $12.0 million related to its Sutherland Generating Station.

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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 + Details
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