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(Net Realized and Unrealized Gains and Losses) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
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Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Gain (Loss) on Investments [Abstract] |  |  |  |
Net realized investment gains (losses), pre-tax | $ 23.7 | $ 38.3 | $ 40.5 | $ 67.7
Net unrealized investment gains (losses) pre-tax, total changes in fair value reflected in earnings | 49.0 | (35.4) | 82.7 | (31.3)
Net Realized and Unrealized Gain (Loss) on Trading Securities | 72.7 | 2.9 | 123.2 | 36.4
Trading Securities, Tax on Realized and Unrealized Holding Gain (Loss) on Investments | 12.3 | 1.4 | 28.3 | 12.7
Trading Securities Realized and Unrealized Holding Gain (Loss) on Investments after Tax | $ 60.4 | $ 1.5 | $ 94.9 | $ 23.7

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- Definition The sum of the realized and unrealized net gain (loss) on trading securities during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 + Details
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- Definition This item represents the gain (loss) realized during the period from the sale of trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph c -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 + Details
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- Definition The aggregate of the change in unrealized holding gain (loss) and foreign currency gain (loss) included in earnings during the reporting period. + References No definition available. + Details
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- Definition Represents the net realized and unrealized investment gains (losses) after income taxes. + References No definition available. + Details
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- Definition Represents the income taxes attributable to realized and unrealized gains (losses) on trading securities. + References No definition available. + Details
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