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Stock Based Compensation (Details) - USD ($) | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 31, 2018 | Aug. 31, 2017 | Jun. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2010
Stock Based Compensation |  |  |  |  |  |  |  |
Expected life | 3 years |  |  |  |  |  |  |
Total charge to operations: |  |  |  |  |  |  |  |
Share based compensation charged to operations |  |  |  | $ 971,000 | $ 684,000 | $ 2,653,000 | $ 2,341,000 |
Restricted stock |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Vesting period |  |  |  |  |  | 5 years |  |
Summary of the activity of the incentive plans |  |  |  |  |  |  |  |
Average per share grant price (in dollars per share) |  |  |  |  |  | $ 25.31 | $ 24.75 |
Deferred compensation to be recognized over vesting period |  |  |  |  |  | $ 3,664,000 | $ 3,467,000 |
Non-vested beginning of year (in shares) | 651,500 |  |  | 651,500 | 612,900 | 612,900 | 591,750 |
Number of non-vested shares: |  |  |  |  |  |  |  |
Non-vested beginning of year (in shares) | 651,500 |  |  | 651,500 | 612,900 | 612,900 | 591,750 |
Number of shares granted |  |  |  |  |  | 144,750 | 140,100 |
Vested during year (in shares) |  |  |  |  |  | (106,000) | (118,450) |
Forfeitures (in shares) |  |  |  | (250) |  | (400) | (500) |
Non-vested end of year (in shares) |  |  | 612,900 | 651,250 | 612,900 | 651,250 | 612,900 |
Restricted stock and RSU grants: |  |  |  |  |  |  |  |
Weighted average per share value of non-vested shares (based on grant price) (in dollars per share) |  |  |  | $ 23.83 | $ 22.89 | $ 23.83 | $ 22.89 |
Value of stock vested during the year (based on grant price) |  |  |  |  |  | $ 2,289,000 | $ 3,008,000 |
Weighted average per share value of shares forfeited during the year (based on grant price) (in dollars per share) |  |  |  | $ 23.39 |  | $ 23.59 | $ 8.37 |
Total charge to operations: |  |  |  |  |  |  |  |
Share based compensation charged to operations |  |  |  | $ 763,000 | $ 684,000 | $ 2,263,000 | $ 2,255,000 |
Compensation costs related to non-vested awards that have not yet been recognized |  |  |  | $ 7,581,000 |  | $ 7,581,000 |  |
Approximate weighted average vesting period |  |  |  |  |  | 2 years 4 months 24 days |  |
RSUs |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Percentage of units to be vested on satisfaction of performance criteria of average total stockholder return |  |  |  |  |  | 50.00% |  |
Percent of number of units to be vested on satisfaction of performance criteria related to average annual return on capital |  |  |  |  |  | 50.00% |  |
Summary of the activity of the incentive plans |  |  |  |  |  |  |  |
Average per share grant price (in dollars per share) |  |  |  | $ 26.41 | $ 24.03 | $ 26.41 | $ 24.03 |
Deferred compensation to be recognized over vesting period |  |  |  | $ 1,136,000 | $ 919,000 | $ 1,136,000 | $ 919,000 |
Non-vested beginning of year (in shares) | 76,250 |  |  | 76,250 |  | 76,250 | 200,000 |
Number of non-vested shares: |  |  |  |  |  |  |  |
Non-vested beginning of year (in shares) | 76,250 |  |  | 76,250 |  | 76,250 | 200,000 |
Number of shares granted |  |  |  | 76,250 | 76,250 | 76,250 | 76,250 |
Vested during year (in shares) |  |  |  |  |  |  | (113,584) |
Forfeitures (in shares) |  |  |  |  |  | 0 | (86,416) |
Non-vested end of year (in shares) |  |  |  | 152,500 | 76,250 | 152,500 | 76,250 |
Total charge to operations: |  |  |  |  |  |  |  |
Share based compensation charged to operations |  |  |  | $ 208,000 |  | $ 390,000 | $ 86,000 |
Compensation costs related to non-vested awards that have not yet been recognized |  |  |  | $ 1,717,000 |  | $ 1,717,000 |  |
Approximate weighted average vesting period |  |  |  |  |  | 2 years 3 months 18 days |  |
TSR awards |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Dividend rate | 6.82% |  |  |  |  |  |  |
Risk-free interest rate minimum | 2.18% |  |  |  |  |  |  |
Risk-free interest rate maximum | 2.70% |  |  |  |  |  |  |
Expected price volatility minimum | 22.29% |  |  |  |  |  |  |
Expected price volatility maximum | 25.99% |  |  |  |  |  |  |
2016 Incentive Plan |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Maximum number of shares authorized for issuance |  |  |  | 750,000 |  | 750,000 |  |
Shares vested pursuant to Plan |  |  |  |  |  | 3,000 |  |
2016 Incentive Plan | Restricted stock |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Number of shares issued |  |  |  |  |  | 284,850 |  |
Number of non-vested shares: |  |  |  |  |  |  |  |
Forfeitures (in shares) |  |  |  |  |  | (300) |  |
2016 Incentive Plan | RSUs |  |  |  |  |  |  |  |
Number of non-vested shares: |  |  |  |  |  |  |  |
Non-vested end of year (in shares) |  |  |  | 152,500 |  | 152,500 |  |
2012 Incentive Plan |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Number of shares issued |  |  |  |  |  | 500,700 |  |
Shares forfeited pursuant to Plan |  |  |  |  |  | 3,550 |  |
Shares vested pursuant to Plan |  |  |  |  |  | 127,450 |  |
Additional awards authorized |  |  |  |  |  | 0 |  |
2009 Incentive Plan | RSUs |  |  |  |  |  |  |  |
Stock Based Compensation |  |  |  |  |  |  |  |
Number of shares issued |  | 113,584 |  |  |  |  |  |
Number of non-vested shares: |  |  |  |  |  |  |  |
Number of shares granted |  |  |  |  |  |  |  | 200,000
Vested during year (in shares) |  |  | (113,584) |  |  |  |  |
Pay-for-performance program | 2017 RSU grants | General and administrative expense |  |  |  |  |  |  |  |
Summary of the activity of the incentive plans |  |  |  |  |  |  |  |
Deferred compensation to be recognized over vesting period |  |  |  |  |  | $ 1,066,000 |  |
Pay-for-performance program | 2018 RSU grants | General and administrative expense |  |  |  |  |  |  |  |
Summary of the activity of the incentive plans |  |  |  |  |  |  |  |
Deferred compensation to be recognized over vesting period |  |  |  |  |  | $ 1,136,000 |  |

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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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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