v2.4.0.6

Receivables (Narrative) (Details) (USD $) In Millions, unless otherwise specified |  |  | 12 Months Ended |  |  |  | 12 Months Ended | 1 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2012 Whiting Petroleum Corporation [Member] | Dec. 31, 2011 Whiting Petroleum Corporation [Member] | Dec. 31, 2012 IPL [Member] | Dec. 31, 2011 IPL [Member] | Dec. 31, 2012 IPL [Member] Maximum [Member] | Dec. 31, 2011 IPL [Member] Maximum [Member] | Dec. 31, 2010 IPL [Member] Maximum [Member] | Dec. 31, 2012 IPL [Member] March 2012 Through March 2014 [Member] Maximum [Member] | Dec. 31, 2012 IPL [Member] March 2012 Through March 2014 [Member] Minimum [Member] | Dec. 31, 2011 IPL and WPL [Member] | Dec. 31, 2012 Franklin County Wind Project [Member] American Recovery and Reinvestment Act of 2009 [Member] | Feb. 28, 2013 Franklin County Wind Project [Member] American Recovery and Reinvestment Act of 2009 [Member] Subsequent Event [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash proceeds to be received from third-party |  |  |  |  |  |  | $ 160.0 | $ 160.0 | $ 160.0 | $ 180.0 | $ 150.0 |  |  |
Receivables sold |  |  |  |  | 198.4 | 195.3 |  |  |  |  |  |  |  |
Obligations to pay on tax benefits, percentage |  |  | 90.00% |  |  |  |  |  |  |  |  |  |  |
Customer accounts receivable and unbilled revenues | 94.9 | 88.1 | 27.0 | 27.0 | 95.0 | 75.2 |  |  |  |  |  |  |  |
Customer accounts receivable, financing payment term |  |  |  |  |  |  |  |  |  |  |  | 5 years |  |
Cash grant request, percentage of qualifying project expenditures |  |  |  |  |  |  |  |  |  |  |  |  |  | 30.00%
Accounts receivable, expected amount due | 209.4 | 114.9 |  |  |  |  |  |  |  |  |  |  | 62.0 |
Decrease in non-regulated generation property, plant and equipment |  |  |  |  |  |  |  |  |  |  |  |  | 62 |
Timing difference between book and tax basis related to expected grant proceeds, percentage |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |
Permanent timing difference between book and tax basis related to expected grant proceeds, percentage |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |
Long-term deferred income tax asset recorded |  |  |  |  |  |  |  |  |  |  |  |  | $ 20 |

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- Definition Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection. + 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 210.5-02.3-4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph a(1) -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 4 -Article 5 + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed after one year (or the normal operating cycle, if longer). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Deferred Tax Asset -URI http://asc.fasb.org/extlink&oid=6510090 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42, 43, 289 -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e31917-109318 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e31931-109318 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 + Details
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- Definition Carrying amounts due as of the balance sheet date from parties or arising from transactions not otherwise specified in the taxonomy. + 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 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 8 -Article 5 + Details
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- Definition The cash inflow associated with the proceeds from sale and collection of receivables during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph a -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 -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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