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STOCK-BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 26, 2015 | Dec. 27, 2014
Stock Based Compensation |  |  |
Shares of common stock available for issuance | 706,000 |  |
Number of Shares |  |  |
Exercised (in shares) | (109,893) | (169,493) | (194,627)
Stock option plans |  |  |
Stock Based Compensation |  |  |
Compensation expense (included in selling, general and administrative expenses) | $ 5,782 | $ 5,137 | $ 4,461
Tax benefits associated with compensation expense | $ 2,197 | $ 1,952 | $ 1,695
Weighted average period over which unrecognized stock option compensation cost would be recognized | 2 years 1 month 25 days |  |
Unrecognized stock option compensation expense | $ 9,872 |  |
Assumptions used in estimating fair value of each option grant |  |  |
Expected volatility (as a percent) | 33.88% | 34.13% | 32.27%
Risk-free interest rate (as a percent) | 1.83% | 1.58% | 1.43%
Expected life from vesting date | 3 years | 3 years | 3 years
Dividend yield (as a percent) | 1.13% | 0.94% | 0.75%
Number of Shares |  |  |
Balance at the beginning of the period (in shares) | 849,609 | 768,595 | 795,221
Granted (in shares) | 85,092 | 291,708 | 177,717
Exercised (in shares) | (109,893) | (169,493) | (194,627)
Forfeited (in shares) | (31,635) | (41,201) | (9,716)
Balance at the end of the period (in shares) | 793,173 | 849,609 | 768,595
Options vested or expected to vest (in shares) | 774,139 | 818,300 | 746,974
Options exercisable (in shares) | 469,844 | 409,068 | 450,539
Weighted Average Exercise Price |  |  |
Balance at the beginning of the period (in dollars per share) | $ 117,420 | $ 113,720 | $ 99,290
Granted (in dollars per share) | 151,370 | 104,890 | 132,940
Exercised (in dollars per share) | (101,690) | (74,370) | (71,670)
Forfeited (in dollars per share) | (129,360) | (137,020) | (126,230)
Balance at the end of the period (in dollars per share) | 122,770 | 117,420 | 113,720
Options vested or expected to vest (in dollars per share) | 124,180 | 117,610 | 113,060
Options exercisable (in dollars per share) | $ 123,750 | $ 119,430 | $ 97,290
Weighted Average Remaining Contractual Term |  |  |
Options outstanding | 4 years 9 months 11 days | 5 years 2 months 4 days | 4 years 8 months 26 days
Options vested or expected to vest | 4 years 8 months 31 days | 5 years 1 month 16 days | 4 years 8 months 8 days
Options exercisable | 3 years 11 months 15 days | 3 years 8 months 26 days | 3 years 7 months 2 days
Aggregate Intrinsic Value |  |  |
Options outstanding | $ 16,640 | $ 4,536 | $ 15,983
Options vested or expected to vest | 16,200 | 4,456 | 15,981
Options exercisable | $ 9,056 | $ 3,376 | $ 15,944
Other option disclosures |  |  |
Weighted average per share fair value of option granted | $ 40.00 | $ 27.91 | $ 33.94
Stock option plans | Maximum |  |  |
Stock Based Compensation |  |  |
Vesting period of options | 6 years |  |
Expiration period of grant | 10 years |  |
Stock option plans | Minimum |  |  |
Stock Based Compensation |  |  |
Vesting period of options | 3 years |  |
Expiration period of grant | 6 years |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income 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 (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&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://www.xbrl.org/2003/role/presentationRef -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=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over 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 (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + 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 (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + 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 + 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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