STOCK AWARD PLANS (Details) - USD ($) | 3 Months Ended | 9 Months Ended |
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 |
STOCK AWARD PLANS [Abstract] | | | | |
Compensation cost | $ 3,296,000 | $ 3,127,000 | $ 8,841,000 | $ 8,378,000 |
Income tax benefit | 1,236,000 | $ 1,161,000 | 3,315,000 | 3,125,000 |
Share based Compensation Plans Combined Disclosure [Abstract] | | | | |
Intrinsic value of stock options exercised | | | 266,000 | 2,555,000 |
Tax benefit from stock options exercised | | | 100,000 | 953,000 |
Intrinsic value of restricted stock vesting | | | 5,587,000 | 9,055,000 |
Tax benefit from restricted stock vesting | | | 2,095,000 | 3,378,000 |
Fair value of options vested | | | 2,495,000 | 2,194,000 |
Fair value of restricted stock vested | | | $ 5,587,000 | $ 9,055,000 |
Fair value of stock options granted (in dollars per share) | | | $ 17.30 | $ 25.18 |
Fair value of stock options granted | | | $ 3,231,000 | $ 2,893,000 |
Stock Options [Member] | | | | |
Share based Compensation Plans Combined Disclosure [Abstract] | | | | |
Unrecognized compensation cost related to unvested awards | 4,080,000 | | $ 4,080,000 | |
Weighted average period of recognition in years | | | 1 year 8 months 12 days | |
Fair Value Assumptions [Abstract] | | | | |
Dividend yield | | | 0.00% | 0.00% |
Average risk-free interest rate | | | 1.50% | 1.30% |
Stock price volatility | | | 30.00% | 33.00% |
Estimated option term | | | 6 years | 6 years |
Restricted Stock [Member] | | | | |
Share based Compensation Plans Combined Disclosure [Abstract] | | | | |
Unrecognized compensation cost related to unvested awards | $ 20,218,000 | | $ 20,218,000 | |
Weighted average period of recognition in years | | | 3 years 4 months 24 days | |
Employee Stock Award Plan [Member] | | | | |
Stock Award Plan Information [Abstract] | | | | |
Term of grant | | | 7 years | |
Vesting period | | | 3 years | |
Shares available for future grants (in shares) | 1,987,792 | | 1,987,792 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | | | | |
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward] | | | | |
Outstanding at Period Start, (in shares) | | | 430,432 | |
Granted (in shares) | | | 186,706 | |
Forfeited (in shares) | | | (16,017) | |
Outstanding at Period End (in shares) | 601,121 | | 601,121 | |
Weighted Average Exercise Price [Abstract] | | | | |
Outstanding at Period Start (in dollars per share) | | | $ 71.01 | |
Granted (in dollars per share) | | | 53.50 | |
Forfeited (in dollars per share) | | | 80.17 | |
Outstanding at Period End (in dollars per share) | $ 65.33 | | 65.33 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | First Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 36.35 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 31.35 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 16,910 | | 16,910 | |
Weighted Average Remaining Contractual Life | | | 4 months 24 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 32.82 | | $ 32.82 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 16,910 | | 16,910 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 32.82 | | $ 32.82 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | Second Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 51.23 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 46.74 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 212,335 | | 212,335 | |
Weighted Average Remaining Contractual Life | | | 5 years | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 50.03 | | $ 50.03 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 56,629 | | 56,629 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 46.74 | | $ 46.74 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | Third Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 74.99 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 64.89 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 302,735 | | 302,735 | |
Weighted Average Remaining Contractual Life | | | 4 years 3 months 18 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 70.29 | | $ 70.29 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 202,309 | | 202,309 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 69.51 | | $ 69.51 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | Fourth Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 96.85 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 93.64 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 33,987 | | 33,987 | |
Weighted Average Remaining Contractual Life | | | 4 years 3 months 18 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 94.31 | | $ 94.31 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 22,658 | | 22,658 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 94.31 | | $ 94.31 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | Fifth Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 104.37 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 101.46 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 35,154 | | 35,154 | |
Weighted Average Remaining Contractual Life | | | 4 years 4 months 24 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 102.60 | | $ 102.60 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 23,436 | | 23,436 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 102.60 | | $ 102.60 | |
Employee Stock Award Plan [Member] | Stock Options [Member] | Full Exercise Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 104.37 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 31.35 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 601,121 | | 601,121 | |
Weighted Average Remaining Contractual Life | | | 4 years 6 months | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 65.33 | | $ 65.33 | |
Aggregate Intrinsic Value, Options Outstanding | $ 3,071,000 | | $ 3,071,000 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 321,942 | | 321,942 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 67.73 | | $ 67.73 | |
Aggregate Intrinsic Value, Options Exercisable | $ 1,369,000 | | $ 1,369,000 | |
Employee Stock Award Plan [Member] | Restricted Stock [Member] | | | | |
Unvested Restricted Stock Award Shares [Roll Forward] | | | | |
Nonvested balance beginning of period (in shares) | | | 311,727 | |
Granted (in shares) | | | 190,150 | |
Vested (in shares) | | | (104,939) | |
Forfeited (in shares) | | | (19,393) | |
Nonvested balance end of period (in shares) | 377,545 | | 377,545 | |
Weighted Average Grant Date Fair Value Per Share [Abstract] | | | | |
Nonvested balance beginning of period (in dollars per share) | | | $ 75.73 | |
Granted (in dollars per share) | | | 53.55 | |
Vested (in dollars per share) | | | 69.95 | |
Forfeited (in dollars per share) | | | 76.04 | |
Nonvested balance end of period (in dollars per share) | $ 66.15 | | $ 66.15 | |
2000 Director Plan [Member] | | | | |
Stock Award Plan Information [Abstract] | | | | |
Term of grant | | | 10 years | |
Vesting period | | | 6 months | |
Shares available for future grants (in shares) | 522,457 | | 522,457 | |
2000 Director Plan [Member] | Stock Options [Member] | | | | |
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward] | | | | |
Outstanding at Period Start, (in shares) | | | 220,429 | |
Exercised (in shares) | | | (9,000) | |
Forfeited (in shares) | | | (6,000) | |
Outstanding at Period End (in shares) | 205,429 | | 205,429 | |
Weighted Average Exercise Price [Abstract] | | | | |
Outstanding at Period Start (in dollars per share) | | | $ 64.37 | |
Exercised (in dollars per share) | | | 35.72 | |
Forfeited (in dollars per share) | | | 99.52 | |
Outstanding at Period End (in dollars per share) | $ 64.60 | | 64.60 | |
2000 Director Plan [Member] | Stock Options [Member] | First Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 36.82 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 29.60 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 21,000 | | 21,000 | |
Weighted Average Remaining Contractual Life | | | 1 year 1 month 6 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 32.69 | | $ 32.69 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 21,000 | | 21,000 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 32.69 | | $ 32.69 | |
2000 Director Plan [Member] | Stock Options [Member] | Second Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 56.45 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 41.24 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 71,276 | | 71,276 | |
Weighted Average Remaining Contractual Life | | | 2 years 10 months 24 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 52.34 | | $ 52.34 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 71,276 | | 71,276 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 52.34 | | $ 52.34 | |
2000 Director Plan [Member] | Stock Options [Member] | Third Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 62.48 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 61.89 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 41,153 | | 41,153 | |
Weighted Average Remaining Contractual Life | | | 5 years | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 62.34 | | $ 62.34 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 41,153 | | 41,153 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 62.34 | | $ 62.34 | |
2000 Director Plan [Member] | Stock Options [Member] | Fourth Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 99.52 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 75.17 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 72,000 | | 72,000 | |
Weighted Average Remaining Contractual Life | | | 6 years | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 87.35 | | $ 87.35 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 72,000 | | 72,000 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 87.35 | | $ 87.35 | |
2000 Director Plan [Member] | Stock Options [Member] | Full Exercise Price Range [Member] | | | | |
Outstanding and Exercisable Stock options [Abstract] | | | | |
Range of Exercise Prices, upper limit (in dollars per share) | | | 99.52 | |
Range of Exercise Prices, lower limit (in dollars per share) | | | $ 29.60 | |
Options Outstanding [Abstract] | | | | |
Number Outstanding (in shares) | 205,429 | | 205,429 | |
Weighted Average Remaining Contractual Life | | | 4 years 2 months 12 days | |
Weighted Average Exercise Price, Options Outstanding (in dollars per share) | $ 64.60 | | $ 64.60 | |
Aggregate Intrinsic Value, Options Outstanding | $ 1,321,000 | | $ 1,321,000 | |
Options Exercisable [Abstract] | | | | |
Number Exercisable (in shares) | 205,429 | | 205,429 | |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 64.60 | | $ 64.60 | |
Aggregate Intrinsic Value, Options Exercisable | $ 1,321,000 | | $ 1,321,000 | |
2000 Director Plan [Member] | Restricted Stock [Member] | | | | |
Unvested Restricted Stock Award Shares [Roll Forward] | | | | |
Nonvested balance beginning of period (in shares) | | | 1,791 | |
Granted (in shares) | | | 23,074 | |
Vested (in shares) | | | (2,485) | |
Nonvested balance end of period (in shares) | 22,380 | | 22,380 | |
Weighted Average Grant Date Fair Value Per Share [Abstract] | | | | |
Nonvested balance beginning of period (in dollars per share) | | | $ 68.73 | |
Granted (in dollars per share) | | | 64.89 | |
Vested (in dollars per share) | | | 67.66 | |
Nonvested balance end of period (in dollars per share) | $ 64.89 | | $ 64.89 | |