XML 137 R51.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Share-Based Payments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Schedule of Summary of Stock Option Transactions under Share Based Payment Plans |
|  | Number of Shares |  | Weighted Average Exercise Price |  | Weighted Average Remaining Contractual Life in Years |  | Aggregate Intrinsic Value ($ in thousands)
Outstanding at December 31, 2012 |  | 1,096,754 |  |  | $ | 19.36 |  |  |  |  |  |
Granted in 2013 |  | — |  |  | — |  |  |  |  |  |
Exercised in 2013 |  | 182,201 |  |  | 16.98 |  |  |  |  |  |
Forfeited or expired in 2013 |  | 11,114 |  |  | 26.59 |  |  |  |  |  |
Outstanding at December 31, 2013 |  | 903,439 |  |  | $ | 19.75 |  |  | 3.92 |  | $ | 6,705 |
Exercisable at December 31, 2013 |  | 903,439 |  |  | $ | 19.75 |  |  | 3.92 |  | $ | 6,705 |
Schedule of Summary of Restricted Stock Units Transactions under Share-Based Payment Plans |
|  | Number of Shares |  | Weighted Average Grant Date Fair Value
Unvested RSU awards at December 31, 2012 |  | 1,137,370 |  |  | $ | 16.54 |
Granted in 2013 |  | 396,713 |  |  | 21.03 |
Vested in 2013 |  | 416,753 |  |  | 15.01 |
Forfeited in 2013 |  | 20,550 |  |  | 17.24 |
Unvested RSU awards at December 31, 2013 |  | 1,096,780 |  |  | $ | 18.73 |
Schedule of Weighted Average Assumptions for Employee Stock Purchase Plan |
|  | ESPP
|  | 2013 |  | 2012 |  | 2011
Risk-free interest rate |  | 0.11 | % |  | 0.12 |  | 0.13
Expected term |  | 6 months |  |  | 6 months |  | 6 months
Dividend yield |  | 2.4 | % |  | 2.9 |  | 3.0
Expected volatility |  | 19 | % |  | 24 |  | 19
Schedule of Weighted-Average Fair Value of Stock Per Share |
|  | 2013 |  | 2012 |  | 2011
RSUs |  | $ | 21.03 |  |  | 17.62 |  |  | 17.17 |
ESPP: |  |  |  |  |  |  |  |
Six month option |  | 0.97 |  |  | 1.05 |  |  | 0.76 |
Discount of grant date market value |  | 3.24 |  |  | 2.70 |  |  | 2.62 |
Total ESPP |  | 4.21 |  |  | 3.75 |  |  | 3.38 |
Agent Plan: |  |  |  |  |  |  |  |  |
Discount of grant date market value |  | 2.40 |  |  | 1.76 |  |  | 1.62 |

X
- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of employee stock purchase plans and all other option plans, including, but not limited to: (a) expected term, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References No definition available. + Details
Name: | sigi_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanAndOtherOptionPlansValuationAssumptionsTableTextBlock
Namespace Prefix: | sigi_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year. + References No definition available. + Details
Name: | us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for share options (or share units) that were outstanding at the beginning and end of the year, vested and expected to vest, exercisable or convertible at the end of the year, and the number of share options or share units that were granted, exercised or converted, forfeited, and expired during the year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the weighted-average grant-date fair value of equity options or other equity instruments granted during the year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValueTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration