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Stock-Based Compensation (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Stock options additional disclosures [Abstract] |  |  |
Stock-based compensation expense | $ 4,086,000 | $ 3,521,000 | $ 4,305,000
Restricted stock and restricted stock units, weighted average grant date fair value [Abstract] |  |  |
Number of shares available for future grant (in shares) | 3,500,000 |  |
Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Stock awards vesting period | 4 years |  |
Stock awards termination period | 10 years |  |
Stock options [Roll Forward] |  |  |
Outstanding, beginning of period (in shares) | 1,038,342 |  |
Granted (in shares) | 36,316 |  |
Exercised (in shares) | (519,947) |  |
Forfeited (in shares) | 0 |  |
Expired (in shares) | (13,147) |  |
Outstanding, end of period (in shares) | 541,564 | 1,038,342 |
Exercisable, end of period (in shares) | 501,952 |  |
Expected to vest (in shares) | 39,240 |  |
Stock options, weighted average exercise price [Abstract] |  |  |
Outstanding, beginning of period (in dollars per share) | $ 23.10 |  |
Granted (in dollars per share) | 25.85 |  |
Exercised (in dollars per share) | 23.16 |  |
Forfeited (in dollars per share) | 0 |  |
Expired (in dollars per share) | 22.97 |  |
Outstanding, end of period (in dollars per share) | 23.23 | $ 23.10 |
Exercisable, end of period (in dollars per share) | 23.03 |  |
Expected to vest (in dollars per share) | $ 25.76 |  |
Stock options additional disclosures [Abstract] |  |  |
Weighted average remaining contractual term, outstanding, end of period | 3 years 2 months 26 days |  |
Weighted average remaining contractual term, exercisable, end of period | 2 years 9 months 7 days |  |
Weighted average remaining contractual term, expected to vest | 9 years 1 month 10 days |  |
Aggregate intrinsic value, outstanding, end of period | $ 2,541,332 |  |
Aggregate intrinsic value, exercisable, end of period | 2,457,469 |  |
Aggregate intrinsic value, expected to vest | 83,294 |  |
Stock-based compensation expense | 200,000 | $ 100,000 | 200,000
Proceeds from stock options exercised | 12,044,000 | 6,554,000 | 7,927,000
Tax (expense) benefits related to stock options exercised | (43,000) | 313,000 | 178,000
Intrinsic value of stock options exercised | 2,446,000 | 789,000 | 905,000
Fair value of shares vested during the year | 63,000 | $ 393,000 | 766,000
Restricted Stock [Member] |  |  |
Stock options additional disclosures [Abstract] |  |  |
Unrecognized compensation cost | $ 3,700,000 |  |
Unrecognized compensation cost, weighted average period of recognition | 1 year 8 months 12 days |  |
Restricted stock and restricted stock units [Roll Forward] |  |  |
Unvested, beginning of period (in shares) | 52,000 |  |
Forfeited (in shares) | 0 |  |
Vested (in shares) | (29,000) |  |
Unvested, end of period (in shares) | 23,000 | 52,000 |
Restricted stock and restricted stock units, weighted average grant date fair value [Abstract] |  |  |
Unvested, beginning of period (in dollars per share) | $ 23.43 |  |
Forfeited (in dollars per share) | 0 |  |
Vested (in dollars per share) | 22.85 |  |
Unvested, end of period (in dollars per share) | $ 24.17 | $ 23.43 |
Restricted Stock [Member] | Employees [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Stock awards vesting period | 5 years |  |
Restricted Stock [Member] | Non-employee Directors [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Stock awards vesting period | 3 years |  |
Restricted Stock Units (RSUs) [Member] |  |  |
Restricted stock and restricted stock units [Roll Forward] |  |  |
Unvested, beginning of period (in shares) | 638,975 |  |
Forfeited (in shares) | (8,407) |  |
Vested (in shares) | (125,520) |  |
Granted (in shares) | 160,040 |  |
Unvested, end of period (in shares) | 665,088 | 638,975 |
Restricted stock and restricted stock units, weighted average grant date fair value [Abstract] |  |  |
Unvested, beginning of period (in dollars per share) | $ 31.01 |  |
Forfeited (in dollars per share) | 0 |  |
Vested (in dollars per share) | 0 |  |
Granted (in dollars per share) | 24.67 |  |
Unvested, end of period (in dollars per share) | $ 35.73 | $ 31.01 |
Restricted and Deferred Stock Awards [Member] |  |  |
Stock options additional disclosures [Abstract] |  |  |
Stock-based compensation expense | $ 4,200,000 | $ 4,200,000 | 3,800,000
Tax benefit from compensation expense | $ 3,900,000 | $ 2,900,000 | $ 2,400,000

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- Definition The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References No definition available. + Details
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- Definition Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period. + 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 (j) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made 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=6415400&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=6415400&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + 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)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + 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)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Net number of share options (or share units) granted during the period. + 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)(iv)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding. + 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 (e) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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