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Stock-Based Compensation - Additional Information (Detail) - USD ($) | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jan. 31, 2018 | Jul. 31, 2017 | Jan. 31, 2017 | Jul. 31, 2016 | Jan. 31, 2016 | Jul. 31, 2015 | Jan. 31, 2014 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of common stock price paid |  |  |  |  |  |  |  | 85.00% |  |  |
Stock options term |  |  |  |  |  |  |  | 7 years |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 939,000 | 1,471,000 | 1,681,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 28.91 | $ 18.95 | $ 17.66 |
Tax benefit from compensation expense |  |  |  |  |  |  |  | $ 10,462,000 | $ 8,752,000 | $ 8,528,000 |
Total unrecognized expense related to non-vested restricted stock unit awards and stock options |  |  |  |  |  |  |  | $ 42,000,000 |  |  |
Unrecognized expense related to non-vested restricted stock unit awards and stock options expected to be recognized over weighted average period, in years |  |  |  |  |  |  |  | 2 years 3 months 19 days |  |  |
Maximum percent of shares allowed to purchase |  |  |  |  |  |  |  | 10.00% |  |  |
Fair market value |  |  |  |  |  |  |  | $ 25,000 |  |  |
Maximum number of shares allowed to purchase |  |  |  |  |  |  |  | 6,000 |  |  |
Common stock issued to employees |  | 300,000 | 400,000 | 500,000 | 500,000 | 500,000 |  |  |  |  |
Value of common stock issued to employees per share |  | $ 25.53 | $ 21.59 | $ 16.74 | $ 17.57 | $ 16.40 |  |  |  |  |
Number of shares available for grant |  |  |  |  |  |  |  | 8,605,000 | 9,546,000 | 10,914,000 | 12,443,000
Stock Options |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of common stock price paid |  |  |  |  |  |  |  | 100.00% |  |  |
Period of stock granted to employees and executive officers vest in equal annual installments |  |  |  |  |  |  |  | 4 years |  |  |
Cash received from employees, employee stock options exercises |  |  |  |  |  |  |  | $ 6,800,000 | $ 2,900,000 | $ 2,800,000 |
Tax benefit from compensation expense |  |  |  |  |  |  |  | $ 2,500,000 | $ 800,000 | $ 2,100,000 |
Restricted Stock Units |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 939,000 | 1,471,000 | 1,681,000 |
Restricted Stock Units | Employees |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal annual installments |  |  |  |  |  |  |  | 4 years |  |  |
Restricted Stock Units | Director |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Period of stock granted to employees and executive officers vest in equal annual installments |  |  |  |  |  |  |  | 1 year |  |  |
Percentage of awards vesting on the first anniversary of grant date |  |  |  |  |  |  |  | 100.00% |  |  |
TSR Performance-Based Restricted Stock Units |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Total shareholder return performance measurement period |  |  |  |  | 3 years |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, description |  |  |  |  |  |  |  | Capped at four times the grant date value |  |  |
Minimum age of retirement to be eligible for PRSUs |  |  |  |  |  |  | 60 years |  |  |  |
Minimum years of service for retirement to be eligible for PRSUs |  |  |  |  |  |  | 10 years |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 100,000 | 100,000 | 200,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 35.66 | $ 20.29 | $ 18.21 |
Estimated annual dividend amount per share |  |  |  |  |  |  |  | 0.28 | 0.24 | 0.24 |
Stock price |  |  |  |  |  |  |  | $ 28.56 | $ 19.43 | $ 18.10 |
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  | 200.00% |  |  |  |  |  |
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  | 0.00% |  |  |  |  |  |
Employee Stock Purchase Plan |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Number of shares available for grant |  |  |  |  |  |  |  | 3,100,000 |  |  |
PBIT Performance-Based Restricted Stock Units |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Total shareholder return performance measurement period |  |  |  |  | 3 years |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 100,000 | 100,000 |  |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 27.72 | $ 18.71 |  |
PBIT Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  | 200.00% |  |  |  |  |  |
PBIT Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Percentage of vesting of target shares upon performance achieved |  |  |  |  | 0.00% |  |  |  |  |  |
Service-Based Restricted Stock Units | Employees |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 800,000 | 1,200,000 | 1,500,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 28.19 | $ 18.88 | $ 17.51 |
Service-Based Restricted Stock Units | Non Employee Directors And Certain Employees |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 34.48 | $ 18.71 | $ 20.21 |
Service-Based Restricted Stock Units | Executive Officer |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Restricted stock unit awards granted |  |  |  |  |  |  |  | 100,000 | 100,000 | 100,000 |
Weighted average grant date fair value of restricted stock units granted |  |  |  |  |  |  |  | $ 7.13 | $ 5.30 | $ 4.43 |
Subsequent Event |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |  |  |  |  |
Common stock issued to employees | 300,000 |  |  |  |  |  |  |  |  |  |
Value of common stock issued to employees per share | $ 35.59 |  |  |  |  |  |  |  |  |  |

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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + 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 (i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Details
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