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Investment Securities (Rollforward of Fair Value Measurements by Level) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2016 USD ($) Investment | Dec. 31, 2015 USD ($) Investment | Dec. 31, 2014 USD ($)
Investment securities |  |  |
Short-term investments, at amortized cost (which approximates fair value) | $ 287.0 | $ 211.2 |
Fixed maturity investments, at fair value | 4,250.2 | 2,630.2 |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 4,050.9 | 3,343.6 |
Total realized and unrealized gains (losses) | (11.6) | 226.8 |
Amortization/Accretion | (19.3) | (19.6) |
Purchases | 6,381.7 | 2,377.1 |
Sales | (5,385.2) | (2,210.1) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | (61.4) |
Transfers in | 118.0 | 41.8 |
Transfers out | (118.0) | (41.8) |
Fair value investments | 5,039.7 | 4,050.9 | $ 3,343.6
Net realized and unrealized investment gains | 10.3 | 225.4 | 78.5
Trading Securities, Change in Unrealized Holding Gain (Loss) | (267.3) | 152.9 | (79.3)
Discontinued Operations |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Net realized and unrealized investment gains | (1.5) | 15.1 | 205.4
Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 4,134.4 |  |
Fair value investments | 5,195.9 | 4,134.4 |
Level 1 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 1,152.2 | 550.6 |
Total realized and unrealized gains (losses) | 11.3 | 263.0 |
Amortization/Accretion | 0.1 | 0.0 |
Purchases | 2,243.7 | 814.5 |
Sales | (2,794.8) | (825.7) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | (43.5) |
Transfers in | 0.0 | 0.0 |
Transfers out | 0.0 | (1.2) |
Fair value investments | 612.5 | 1,152.2 | 550.6
Level 1 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 1,363.5 |  |
Fair value investments | 887.0 | 1,363.5 |
Level 2 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 2,531.4 | 2,372.9 |
Total realized and unrealized gains (losses) | 0.2 | (13.7) |
Amortization/Accretion | (19.4) | (19.6) |
Purchases | 3,979.8 | 1,436.0 |
Sales | (2,491.5) | (1,286.0) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | 0.0 |
Transfers in | 118.0 | 41.8 |
Transfers out | 0.0 | 0.0 |
Fair value investments | 4,118.5 | 2,531.4 | 2,372.9
Level 2 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 2,531.4 |  |
Fair value investments | 4,131.2 | 2,531.4 |
Level 3 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Trading Securities, Change in Unrealized Holding Gain (Loss) | 6.2 | (23.1) | 7.7
Level 3 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 239.5 |  |
Fair value investments | 177.7 | 239.5 |
Prospector |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Net realized and unrealized investment gains |  | 0.8 |
Symetra |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Purchases |  | 394.5 |
Symetra | Level 1 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Purchases |  | 394.5 |
Trading Securities, Change in Unrealized Holding Gain (Loss) |  | 258.8 |
Star & Shield Insurance Exchange [Member] | Fixed maturity investments |  |  |
Investment securities |  |  |
Fixed maturity investments, at fair value | 6.6 | 9.5 | 10.1
Common equity securities |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Trading Securities, Change in Unrealized Holding Gain (Loss) | (254.6) | 207.6 | (83.0)
Common equity securities | Level 3 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 0.0 | 39.5 |
Total realized and unrealized gains (losses) | 0.0 | 7.8 |
Amortization/Accretion | 0.0 | 0.0 |
Sales | 0.0 | (43.7) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | (3.6) |
Transfers in | 0.0 | 0.0 |
Transfers out | 0.0 | 0.0 |
Fair value investments | 0.0 | 0.0 | 39.5
Trading Securities, Change in Unrealized Holding Gain (Loss) | 0.0 | (9.0) | 5.8
Fixed maturity investments |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Trading Securities, Change in Unrealized Holding Gain (Loss) | (12.1) | (15.6) | 11.3
Fixed maturity investments | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 2,639.7 |  |
Fair value investments | 4,256.8 | 2,639.7 |
Fixed maturity investments | Level 1 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 134.0 |  |
Fair value investments | 269.4 | 134.0 |
Fixed maturity investments | Level 2 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 2,435.7 |  |
Fair value investments | 3,987.4 | 2,435.7 |
Fixed maturity investments | Level 3 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 70.0 | 76.4 |
Total realized and unrealized gains (losses) | 0.1 | (1.1) |
Amortization/Accretion | 0.0 | 0.0 |
Purchases | 120.8 | 35.3 |
Sales | (72.9) |  |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | 0.0 |
Transfers in | 0.0 | 0.0 |
Transfers out | (118.0) | (40.6) |
Fair value investments | $ 0.0 | $ 70.0 | 76.4
Number of investments | Investment | 3 | 6 |
Trading Securities, Change in Unrealized Holding Gain (Loss) | $ 0.1 | $ (1.1) | 1.9
Fixed maturity investments | Level 3 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 70.0 |  |
Fair value investments | 0.0 | 70.0 |
Other long-term investments |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Trading Securities, Change in Unrealized Holding Gain (Loss) | (0.6) | (39.1) | (7.6)
Other long-term investments | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 169.5 |  |
Fair value investments | 177.7 | 169.5 |
Other long-term investments | Level 1 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 0.0 |  |
Fair value investments | 0.0 | 0.0 |
Other long-term investments | Level 2 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 0.0 |  |
Fair value investments | 0.0 | 0.0 |
Other long-term investments | Level 3 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 169.5 | 125.9 |
Total realized and unrealized gains (losses) | 6.1 | (20.0) |
Amortization/Accretion | 0.0 | 0.0 |
Purchases | 2.2 | 76.5 |
Sales | (0.1) | (12.9) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | 0.0 |
Transfers in | 0.0 | 0.0 |
Transfers out | 0.0 | 0.0 |
Fair value investments | 177.7 | 169.5 | 125.9
Trading Securities, Change in Unrealized Holding Gain (Loss) | 6.1 | (13.0) | 0.0
Other long-term investments | Level 3 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 169.5 |  |
Fair value investments | 177.7 | 169.5 |
Carrying value of investment accounted for using the equity method | 3.5 | 3.8 | 5.2
Other long-term investments | Affordable Housing Development Fund [Member] |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 14.7 | 16.8 |
Fair value investments | 12.3 | 14.7 | 16.8
Short-term Investments [Member] | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 211.3 | 376.8 |
Fair value investments | 287.1 | 211.3 | 376.8
Short-term Investments [Member] | Level 1 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 211.3 |  |
Fair value investments | 274.4 | 211.3 |
Short-term Investments [Member] | Level 2 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 0.0 |  |
Fair value investments | 12.7 | 0.0 |
Short-term Investments [Member] | Level 3 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 0.0 |  |
Fair value investments | 0.0 | 0.0 |
Short-term Investments [Member] | Star & Shield Insurance Exchange [Member] | Level 1 Inputs | Short-term Investments [Member] |  |  |
Investment securities |  |  |
Short-term investments, at amortized cost (which approximates fair value) | 0.1 | 0.1 |
Forward Contracts [Member] |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Trading Securities, Change in Unrealized Holding Gain (Loss) | 0.0 |  |
Forward Contracts [Member] | Level 3 Inputs | Fair value measured on a recurring basis |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | (1.2) |  |
Total hedge and private equity funds included in other long-term investments | Level 3 Inputs |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Fair value investments | 127.8 | 178.3 |
Total realized and unrealized gains (losses) | (6.1) | (9.2) |
Amortization/Accretion | 0.0 | 0.0 |
Purchases | 35.2 | 14.8 |
Sales | (25.9) | (41.8) |
Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates |  | (14.3) |
Transfers in | 0.0 | 0.0 |
Transfers out | 0.0 | 0.0 |
Fair value investments | $ 131.0 | $ 127.8 | $ 178.3

X
- Definition The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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- Definition Fair value portion of investments accounted under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=66022186&loc=d3e32014-111567 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments. + 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 (c)-(e) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 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),9(a)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27405-111563 + Details
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- Definition Fair value portion of investment securities, including, but not limited to, 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 -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(12)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: 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=27723805&loc=d3e24584-111560 Reference 6: 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(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 7: 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=65884222&loc=d3e22054-111558 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 9: 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 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current. + 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(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(g)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(4)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Amount of investments in debt securities classified as trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26626-111562 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 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),1) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562 + Details
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- Definition Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading. + 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 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560 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=73527792&loc=d3e27357-111563 + Details
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- Definition This element represents the amount of the total realized and unrealized (holding) gains or losses for the period which are included in the statement of income. + References No definition available. + Details
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- Definition This element represents transfers in to one of the levels in the fair value hierarchy for assets measured at fair value on a recurring basis. + References No definition available. + Details
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- Definition This element represents transfers out of one of the levels in the fair value hierarchy for assets measured at fair value on a recurring basis. + References No definition available. + Details
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Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
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- Definition Net change in investments related to purchases and sales of consolidated/unconsolidated affiliates + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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- Definition Number of Investments + References No definition available. + Details
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- Details
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- Details
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