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Reserve for Property-Liability Insurance Claims and Claims Expense (Details 2) - USD ($) $ in Millions | 9 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | $ 321 |
Auto |  |
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | 336 |
Catastrophe |  |
Increase (decrease) in claims and claims expense |  |
Total incurred | 2,640 | $ 2,270
Non Catastrophe Reestimates | Homeowners |  |
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | 86 |
Reserve Adjustments | Discontinued Lines and Coverages Product Line |  |
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | 93 |
Reserve Adjustments | Other personal lines |  |
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | (8) |
Catastrophe Loss Re-estimates |  |
Increase (decrease) in claims and claims expense |  |
Prior years claims and claims adjust expense, favorable | $ 10 |

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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred and costs incurred in the claim settlement process. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 + Details
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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-18) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915 + Details
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