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Investment Securities (Fair Value Measurement by Level) (Details) (USD $) In Millions, unless otherwise specified |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended |  |  |
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Dec. 31, 2012 | Mar. 31, 2013 Fair Value | Dec. 31, 2012 Fair Value | Mar. 31, 2012 Fair Value | Dec. 31, 2011 Fair Value | Mar. 31, 2013 Level 1 Inputs | Dec. 31, 2012 Level 1 Inputs | Mar. 31, 2012 Level 1 Inputs | Dec. 31, 2011 Level 1 Inputs | Mar. 31, 2013 Level 2 Inputs | Dec. 31, 2012 Level 2 Inputs | Mar. 31, 2012 Level 2 Inputs | Dec. 31, 2011 Level 2 Inputs | Mar. 31, 2013 Debt securities issued by corporations | Dec. 31, 2012 Debt securities issued by corporations | Mar. 31, 2013 Mortgage-backed and asset-backed securities Fair Value | Dec. 31, 2012 Mortgage-backed and asset-backed securities Fair Value | Mar. 31, 2013 Mortgage-backed and asset-backed securities Level 2 Inputs | Dec. 31, 2012 Mortgage-backed and asset-backed securities Level 2 Inputs | Mar. 31, 2013 Mortgage-backed and asset-backed securities Level 3 Inputs | Dec. 31, 2012 Mortgage-backed and asset-backed securities Level 3 Inputs | Mar. 31, 2013 Fixed maturity investments. Level 3 Inputs | Dec. 31, 2012 Fixed maturity investments. Level 3 Inputs | Mar. 31, 2012 Fixed maturity investments. Level 3 Inputs | Dec. 31, 2011 Fixed maturity investments. Level 3 Inputs | Mar. 31, 2013 Common equity securities Level 3 Inputs | Dec. 31, 2012 Common equity securities Level 3 Inputs | Mar. 31, 2012 Common equity securities Level 3 Inputs | Dec. 31, 2011 Common equity securities Level 3 Inputs | Mar. 31, 2013 Convertible fixed maturity investments Level 3 Inputs | Dec. 31, 2012 Convertible fixed maturity investments Level 3 Inputs | Mar. 31, 2012 Convertible fixed maturity investments Level 3 Inputs | Dec. 31, 2011 Convertible fixed maturity investments Level 3 Inputs | Mar. 31, 2013 Other long-term investments Level 3 Inputs | Dec. 31, 2012 Other long-term investments Level 3 Inputs | Mar. 31, 2012 Other long-term investments Level 3 Inputs | Dec. 31, 2011 Other long-term investments Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis U.S. Government and agency obligations Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis U.S. Government and agency obligations Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis U.S. Government and agency obligations Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis U.S. Government and agency obligations Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis U.S. Government and agency obligations Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis U.S. Government and agency obligations Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis U.S. Government and agency obligations Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis U.S. Government and agency obligations Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Consumer Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Industrial Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Financials Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Financials Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Financials Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Communications Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Communications Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Communications Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Basic materials Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Energy Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Energy Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Energy Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Utilities Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Technology Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Technology Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Technology Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Other: Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Other: Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Debt securities issued by corporations Other: Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Municipal obligations Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Municipal obligations Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Municipal obligations Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Municipal obligations Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Municipal obligations Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Municipal obligations Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Municipal obligations Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Municipal obligations Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Mortgage-backed and asset-backed securities Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Foreign government, agency and provincial obligations Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Non-cumulative perpetual preference shares Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Fixed maturity investments. Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Fixed maturity investments. Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Fixed maturity investments. Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Fixed maturity investments. Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Fixed maturity investments. Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Fixed maturity investments. Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Fixed maturity investments. Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Fixed maturity investments. Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Short-term investments Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Short-term investments Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Short-term investments Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Short-term investments Level 1 Inputs | Mar. 31, 2012 Fair value measured on a recurring basis Short-term investments Level 1 Inputs | Dec. 31, 2011 Fair value measured on a recurring basis Short-term investments Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Short-term investments Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Short-term investments Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Short-term investments Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Short-term investments Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Consumer Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Consumer Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Consumer Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Consumer Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Consumer Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Consumer Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Consumer Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Consumer Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Financials Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Financials Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Financials Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Financials Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Financials Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Financials Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Financials Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Financials Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Communications Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Communications Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Communications Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Communications Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Communications Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Communications Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Communications Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Communications Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Basic materials Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Basic materials Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Basic materials Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Basic materials Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Basic materials Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Basic materials Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Basic materials Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Basic materials Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Energy Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Energy Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Energy Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Energy Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Energy Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Energy Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Energy Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Energy Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Utilities Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Utilities Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Utilities Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Utilities Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Utilities Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Utilities Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Utilities Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Utilities Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Technology Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Technology Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Technology Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Technology Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Technology Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Technology Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Technology Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Technology Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Other: Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Other: Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Other: Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Other: Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Other: Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Other: Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Other: Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Other: Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Common equity securities Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Common equity securities Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Convertible fixed maturity investments Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Convertible fixed maturity investments Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Convertible fixed maturity investments Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Convertible fixed maturity investments Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Convertible fixed maturity investments Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Convertible fixed maturity investments Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Convertible fixed maturity investments Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Convertible fixed maturity investments Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Other long-term investments Fair Value | Dec. 31, 2012 Fair value measured on a recurring basis Other long-term investments Fair Value | Mar. 31, 2013 Fair value measured on a recurring basis Other long-term investments Level 1 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Other long-term investments Level 1 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Other long-term investments Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Other long-term investments Level 2 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Other long-term investments Level 3 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Other long-term investments Level 3 Inputs | Mar. 31, 2012 Fair value measured on a recurring basis Other long-term investments Level 3 Inputs | Dec. 31, 2011 Fair value measured on a recurring basis Other long-term investments Level 3 Inputs | Mar. 31, 2013 Fair value measured on a recurring basis Forward Contracts Level 2 Inputs | Dec. 31, 2012 Fair value measured on a recurring basis Forward Contracts Level 2 Inputs | Mar. 31, 2013 Segment, Discontinued Operations | Dec. 31, 2012 Segment, Discontinued Operations | Mar. 31, 2012 Segment, Discontinued Operations
Investment securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value investments |  | $ 6,580.6 | [1],[2] | $ 6,950.7 | [1],[2] | $ 6,706.3 | [3],[4] | $ 7,500.8 | [3],[4] | $ 1,386.4 | [5] | $ 1,355.1 | [5] | $ 1,105.8 | [6] | $ 1,033.1 | [6] | $ 4,795.9 | $ 5,206.1 | $ 5,115.0 | $ 6,088.2 | $ 2,411.1 | [7] | $ 2,385.1 | [7] | $ 1,707.3 | $ 2,095.6 | $ 1,677.2 | $ 2,073.5 | $ 30.1 | $ 22.1 | $ 101.0 | $ 92.9 | $ 179.2 | $ 78.9 | $ 36.8 | $ 37.3 | $ 32.8 | $ 32.3 | $ 0 | $ 0 | $ 0 | $ 0 | $ 260.5 | $ 259.3 | $ 273.5 | [3] | $ 268.3 | [3],[4] | $ 7,235.0 | $ 7,581.3 | $ 2,040.8 | $ 1,985.7 | $ 4,795.9 | $ 5,206.1 | $ 398.3 | $ 389.5 | $ 435.5 | $ 440.1 | $ 364.6 | $ 369.1 | $ 70.9 | $ 71.0 | $ 0 | $ 0 | $ 2,409.7 | $ 2,385.1 | $ 0 | $ 1.0 | $ 2,409.7 | $ 2,384.1 | $ 0 | $ 0 | $ 735.5 | $ 727.1 | $ 0 | $ 0 | $ 735.5 | $ 727.1 | $ 0 | $ 0 | $ 308.0 | $ 330.8 | $ 0 | $ 0 | $ 308.0 | $ 330.8 | $ 0 | $ 0 | $ 378.4 | $ 401.4 | $ 0 | $ 1.0 | $ 378.4 | $ 400.4 | $ 0 | $ 0 | $ 331.6 | $ 276.1 | $ 0 | $ 0 | $ 331.6 | $ 276.1 | $ 0 | $ 0 | $ 211.6 | $ 189.1 | $ 0 | $ 0 | $ 211.6 | $ 189.1 | $ 0 | $ 0 | $ 183.2 | $ 181.5 | $ 0 | $ 0 | $ 183.2 | $ 181.5 | $ 0 | $ 0 | $ 202.3 | $ 204.2 | $ 0 | $ 0 | $ 202.3 | $ 204.2 | $ 0 | $ 0 | $ 53.0 | $ 54.0 | $ 0 | $ 0 | $ 53.0 | $ 54.0 | $ 0 | $ 0 | $ 6.1 | $ 20.9 | $ 0 | $ 0 | $ 6.1 | $ 20.9 | $ 0 | $ 0 | $ 5.2 | $ 5.2 | $ 0 | $ 0 | $ 5.2 | $ 5.2 | $ 0 | $ 0 | $ 1,707.3 | $ 2,095.6 | $ 0 | $ 0 | $ 1,677.2 | $ 2,073.5 | $ 30.1 | $ 22.1 | $ 506.1 | $ 521.9 | $ 48.5 | $ 52.1 | $ 457.6 | $ 469.8 | $ 0 | $ 0 | $ 87.5 | $ 86.4 | $ 0 | $ 0 | $ 16.6 | $ 15.6 | $ 70.9 | $ 70.8 | $ 5,151.3 | [1] | $ 5,534.3 | [8] | $ 413.1 | [1] | $ 422.2 | [8] | $ 4,637.2 | [1] | $ 5,019.2 | [8] | $ 101.0 | [1] | $ 92.9 | [8] | $ 654.4 | $ 630.6 | $ 654.4 | $ 630.6 |  |  | $ 0 | $ 0 | $ 0 | $ 0 | $ 305.8 | $ 255.6 | $ 305.8 | $ 255.6 | $ 0 | $ 0 | $ 0 | $ 0 | $ 320.1 | $ 324.5 | $ 283.3 | $ 286.3 | $ 0 | $ 0.9 | $ 36.8 | $ 37.3 | $ 39.9 | $ 35.2 | $ 39.9 | $ 35.2 | $ 0 | $ 0 | $ 0 | $ 0 | $ 77.6 | $ 103.3 | $ 77.6 | $ 103.3 | $ 0 | $ 0 | $ 0 | $ 0 | $ 86.2 | $ 101.0 | $ 86.2 | $ 101.0 | $ 0 | $ 0 | $ 0 | $ 0 | $ 39.7 | $ 43.6 | $ 39.6 | $ 43.4 | $ 0.1 | $ 0.2 | $ 0 | $ 0 | $ 76.9 | $ 55.0 | $ 76.9 | $ 55.0 | $ 0 | $ 0 | $ 0 | $ 0 | $ 127.0 | $ 111.5 | $ 64.0 | $ 53.1 | $ 63.0 | $ 58.4 | $ 0 | $ 0 | $ 1,073.2 | $ 1,029.7 | $ 973.3 | $ 932.9 | $ 63.1 | $ 59.5 | $ 36.8 | $ 37.3 | $ 95.6 | $ 127.4 | $ 0 | $ 0 | $ 95.6 | $ 127.4 | $ 0 | $ 0 | $ 260.5 | [2] | $ 259.3 | [9] | $ 0 | [2] | $ 0 | [9] | $ 0 | [2] | $ 0 | [9] | $ 260.5 | [2] | $ 259.3 | [9] |  |  |  |  |  |  |
Carrying value of investment accounted for using the equity method |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 654.4 | 630.6 | 877.5 | 846.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34.9 |  | 35.0 |  | 33.0 | 33.2 |  |  |  |  |
Realized and unrealized (losses) gains |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (0.2) | (0.1) |  |  |
Fixed maturity investments reclassified to assets held for sale | $ (338.1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (296.9) | $ (338.1) | $ (111.8)
[1] | Carrying value includes $296.9 that is classified as assets held for sale relating to discontinued operations.
[2] | Excludes carrying value of $34.9 associated with other long-term investment limited partnerships accounted for using the equity method and $(0.2) related to forward contracts.
[3] | Excludes carrying value of $33.0 and $33.2 at March 31, 2012 and January 1, 2012 associated with other long-term investment limited partnerships accounted for using the equity method.
[4] | Carrying value includes $111.8 that is classified as assets held for sale relating to discontinued operations.
[5] | Excludes carrying value of $630.6 and $654.4 at January 1, 2013 and March 31, 2013 and realized and unrealized gain for the period of $0.1 associated with short-term investments classified as level 1.
[6] | Excludes carrying value of $877.5 and $846.0 at March 31, 2012 and January 1, 2012 and realized and unrealized loss for the period of $0.3 associated with short-term investments classified as level 1.
[7] | Credit ratings are assigned based on the following hierarchy: 1) Standard and Poor's Financial Services LLC ("Standard & Poor’s") and 2) Moody’s Investor Service ("Moody's").
[8] | Carrying value includes $338.1 that is classified as assets held for sale relating to discontinued operations.
[9] | Excludes carrying value of $35.0 associated with other long-term investment limited partnerships accounted for using the equity method and $(0.1) related to currency forward contracts.

X
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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 6: 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 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e24584-111560 + Details
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