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Share-Based Payments (Tables) | 12 Months Ended
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Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Schedule of Share-Based Compensation Retired Plans |
December 31, 2017 | Types of Share-Based Payments Issued | Reserve Shares | Awards Outstanding 1
Plan
2005 Omnibus Stock Plan ("2005 Stock Plan") | Qualified and nonqualified stock options, SARs, restricted stock, RSUs, phantom stock, stock bonuses, and other awards in such amounts and with such terms and conditions as it determined, subject to the provisions of the 2005 Stock Plan. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. DEUs are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. | 2,202,532 |  | 277,132 |
Parent's Stock Compensation Plan for Non-employee Directors ("Directors Stock Compensation Plan") | Directors could elect to receive a portion of their annual compensation in shares of the Parent's common stock. | 66,506 |  | 66,506 |
1 Awards outstanding under the 2005 Stock Plan consisted of 47,268 RSUs and 229,864 stock options.
Schedule of Share-Based Compensation ESPP and ASPP Shares Granted |
| 2017 | 2016 | 2015
ESPP Issuances | 75,093 |  | 88,432 |  | 100,944 |
Agent Plan Issuances | 49,794 |  | 69,867 |  | 82,142 |
Schedule of Share-Based Compensation Shares Authorized and Available for Issuance |
As of December 31, 2017 | Authorized | Available for Issuance | Awards Outstanding
Stock Plan | 3,500,000 |  | 2,516,871 |  | 882,490 |
ESPP | 1,500,000 |  | 499,629 |  | — |
Agent Plan | 3,000,000 |  | 1,817,493 |  | — |
Schedule Of Share-Based Compensation Plan Approval |
Plan | Approvals
Stock Plan | Approved effective as of May 1, 2014 by stockholders on April 23, 2014.
Cash Plan | Approved effective April 1, 2005 by stockholders on April 27, 2005. Most recently amended and restated plan was approved effective May 1, 2014 by stockholders on April 23, 2014.
ESPP | Approved by stockholders on April 29, 2009 effective July 1, 2009.
Agent Plan | Approved by stockholders on April 26, 2006. Most recently amended and restated plan was approved on December 13, 2016 by the Parent's Board of Directors' Salary and Employee Benefits Committee. The amendment was effective February 1, 2017.
Schedule of Types of Share-Based Payments Issued |
Plan | Types of Share-Based Payments Issued
Stock Plan | Qualified and nonqualified stock options, stock appreciation rights ("SARs"), restricted stock, restricted stock units ("RSUs"), stock grants, and other awards valued in whole or in part by reference to the Parent's common stock. The maximum exercise period for an option grant under this plan is 10 years from the date of the grant. Dividend equivalent units ("DEUs") are earned during the vesting period on RSU grants. The DEUs are reinvested in the Parent's common stock at fair value on each dividend payment date. The requisite service period for grants to employees under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire.
Cash Plan | Cash incentive units (“CIUs”). The initial dollar value of each CIU will be adjusted to reflect the percentage increase or decrease in the total shareholder return on the Parent's common stock over a specified performance period. In addition, for certain grants, the number of CIUs granted will be increased or decreased to reflect our performance on specified performance indicators as compared to targeted peer companies. The requisite service period for grants under this plan is the lesser of: (i) the stated vested date, which is typically three years from issuance; or (ii) the date the employee becomes eligible to retire.
ESPP | Enables employees to purchase shares of the Parent’s common stock. The purchase price is the lower of: (i) 85% of the closing market price at the time the option is granted; or (ii) 85% of the closing price at the time the option is exercised. Shares are generally issued on June 30 and December 31 of each year.
Agent Plan | Quarterly offerings to purchase the Parent's common stock at a 10% discount with a one year restricted period during which the shares purchased cannot be sold or transferred. Only our independent retail insurance agencies and wholesale general agencies, and certain eligible persons associated with the agencies, are eligible to participate in this plan.
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, 2016 |  | 355,391 |  |  | $ | 16.87 |  |  |  |  |  |
Granted in 2017 |  | — |  |  | — |  |  |  |  |  |
Exercised in 2017 |  | (120,496 | ) |  | 19.39 |  |  |  |  |  |
Forfeited or expired in 2017 |  | (5,031 | ) |  | 24.54 |  |  |  |  |  |
Outstanding at December 31, 2017 |  | 229,864 |  |  | $ | 15.38 |  |  | 1.50 |  | $ | 9,958 |
Exercisable at December 31, 2017 |  | 229,864 |  |  | $ | 15.38 |  |  | 1.50 |  | $ | 9,958 |
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, 2016 |  | 916,640 |  |  | $ | 26.20 |
Granted in 2017 |  | 321,928 |  |  | 42.66 |
Vested in 2017 |  | (360,702 | ) |  | 22.78 |
Forfeited in 2017 |  | (12,279 | ) |  | 32.09 |
Unvested RSU awards at December 31, 2017 |  | 865,587 |  |  | $ | 33.66 |
Schedule of Weighted Average Assumptions for Employee Stock Purchase Plan |
|  | ESPP
|  | 2017 |  | 2016 |  | 2015
Risk-free interest rate |  | 1.07 | % |  | 0.47 |  | 0.10
Expected term |  | 6 months |  |  | 6 months |  | 6 months
Dividend yield |  | 1.3 | % |  | 1.7 |  | 2.0
Expected volatility |  | 24 | % |  | 31 |  | 20
Schedule of Weighted-Average Fair Value of Options and Stock Per Share |
|  | 2017 |  | 2016 |  | 2015
RSUs |  | $ | 42.66 |  |  | 32.53 |  |  | 25.22 |
ESPP: |  |  |  |  |  |  |  |
Six month option |  | 2.73 |  |  | 2.63 |  |  | 1.26 |
Discount of grant date market value |  | 7.06 |  |  | 5.23 |  |  | 4.16 |
Total ESPP |  | 9.79 |  |  | 7.86 |  |  | 5.42 |
Agent Plan: |  |  |  |  |  |  |  |  |
Discount of grant date market value |  | 5.04 |  |  | 3.79 |  |  | 2.94 |
Schedule of Compensation Cost for Share-based Payment Arrangements |
($ in millions) | 2017 |  | 2016 |  | 2015
Share-based compensation expense, pre-tax | $ | 31.2 |  |  | 30.3 |  |  | 23.8 |
Income tax benefit, including the benefit related to stock grants that have vested during the year | (15.0 | ) |  | (10.3 | ) |  | (8.0 | )
Share-based compensation expense, after-tax | $ | 16.2 |  |  | 20.0 |  |  | 15.8 |

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