XML 60 R111.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Retirement Plans (Quantitative Disclosures of Retirement Income Plan's Invested Assets that are Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
--- | --- | --- | ---
Alternative Investment Securities Sold |  | 3 |
Fair Value [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | $ 182,774 | $ 171,980 |
Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 137,610 | 116,436 |
Fair Value [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 19,944 | 20,140 |
Fair Value [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 17,016 | 18,958 |
Fair Value [Member] | Short-term Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 7,225 | 15,692 |
Fair Value [Member] | Deposit Administration Contracts [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 979 | 754 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 164,779 | 152,268 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 137,610 | 116,436 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 19,944 | 20,140 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Short-term Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 7,225 | 15,692 |
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Deposit Administration Contracts [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 2,815 | 2,533 |
Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 1,836 | 1,779 |
Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) [Member] | Deposit Administration Contracts [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 979 | 754 |
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 15,180 | 17,179 |
Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] |  |  |
Total assets | 15,180 | 17,179 | 18,764
Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 15,180 | 17,179 |
Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) [Member] | Deposit Administration Contracts [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
International Securities [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 13,205 | 14,277 |
International Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 13,205 | 14,277 |
International Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
International Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Large Capitalization Securities [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 22,200 | 20,580 |
Large Capitalization Securities [Member] | Fair Value [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 11,618 | 11,509 |
Large Capitalization Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 22,200 | 20,580 |
Large Capitalization Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 11,618 | 11,509 |
Large Capitalization Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Large Capitalization Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Large Capitalization Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Large Capitalization Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Small And Mid Capitalization Securities [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 6,750 | 6,785 |
Small And Mid Capitalization Securities [Member] | Fair Value [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 8,326 | 8,631 |
Small And Mid Capitalization Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 6,750 | 6,785 |
Small And Mid Capitalization Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 8,326 | 8,631 |
Small And Mid Capitalization Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Small And Mid Capitalization Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Small And Mid Capitalization Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Small And Mid Capitalization Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Liability Driven Debt Investments [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 36,881 | 27,726 |
Liability Driven Debt Investments [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 36,881 | 27,726 |
Liability Driven Debt Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Liability Driven Debt Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Domestic Core Debt Securities [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 32,930 | 26,991 |
Domestic Core Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 32,930 | 26,991 |
Domestic Core Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Domestic Core Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Global Emerging Market Debt Securities [Member] | Fair Value [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 25,644 | 20,077 |
Global Emerging Market Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 25,644 | 20,077 |
Global Emerging Market Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Global Emerging Market Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Equity Long Short Hedge [Member] | Fair Value [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 1,836 | 1,779 |
Equity Long Short Hedge [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Equity Long Short Hedge [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 1,836 | 1,779 |
Equity Long Short Hedge [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Private Equity [Member] | Fair Value [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 12,586 | 14,492 |
Private Equity [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Private Equity [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Private Equity [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 12,586 | 14,492 |
Real Estate Strategy [Member] | Fair Value [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 2,594 | 2,687 |
Real Estate Strategy [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Real Estate Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | 0 | 0 |
Real Estate Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative Investments [Member] | Fair Value, Measurements, Recurring [Member] |  |  |
Total assets | $ 2,594 | $ 2,687 |

X
- Definition This item represents the number of alternative investments that were sold in the secondary market. + References No definition available. + Details
Name: | sigi_AlternativeInvestmentSecuritiesSold
Namespace Prefix: | sigi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=6867990&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph d(iv)(b)(i) -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b -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 FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 49 -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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant