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Investment Securities (Investment Gains (Losses) For Level 3) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Investment securities |  |  |
Realized gains | $ 221.4 | $ 162.2 | $ 191.6
Realized losses | 116.9 | 94.1 | 123.3
Accounts payable on unsettled investment purchases | 20.5 | 11.4 |
Accounts receivable on unsettled investment sales | 12.1 | 3.9 |
Level 3 Inputs |  |  |
Investment securities |  |  |
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments | 9.8 | 17.7 | (45.6)
Fixed maturity investments | Level 3 Inputs |  |  |
Investment securities |  |  |
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments | (2.3) | 7.7 | (12.2)
Common equity securities | Level 3 Inputs |  |  |
Investment securities |  |  |
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments | 0.9 | 3.0 | (16.6)
Convertible fixed maturity investments | Level 3 Inputs |  |  |
Investment securities |  |  |
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments | 0 | 0 | 0
Other long-term investments | Level 3 Inputs |  |  |
Investment securities |  |  |
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments | $ 11.2 | $ 7.0 | $ (16.8)

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- Definition Amount payable to broker-dealers and clearing organizations, including, but not limited to, securities failed-to-receive, certain deposits received for securities loaned, open transactions, and floor-brokerage payables. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6475717&loc=d3e41645-110958 + Details
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- Definition Amount receivable from broker-dealers and clearing organizations, including, but not limited to, securities failed-to-deliver, certain deposits for securities borrowed, open transactions, good faith and margin deposits, commissions and floor brokerage receivables. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6475717&loc=d3e41645-110958 + Details
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- Definition This item represents the gain realized during the period from the sale of trading securities. + References Reference 1: 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 2: 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=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 4: 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=27724398&loc=d3e27357-111563 + Details
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- Definition This item represents the loss realized during the period from the sale of trading securities. + References Reference 1: 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 2: 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=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 4: 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=27724398&loc=d3e27357-111563 + Details
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