INCENTIVE PLANS - Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding (in shares) | shares	1,138,813
Options outstanding, Weighted-average contractual life remaining	1 year 3 months 15 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 161.96
Options exercisable, Number exercisable (in shares) | shares	1,138,813
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 161.96
$39.00—$99.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, low end of the range (in dollars per share)	39.00
Exercise price, high end of the range (in dollars per share)	$ 99.99
Number outstanding (in shares) | shares	312,309
Options outstanding, Weighted-average contractual life remaining	3 years
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 43.56
Options exercisable, Number exercisable (in shares) | shares	312,309
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 43.56
$100.00—$199.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, low end of the range (in dollars per share)	100.00
Exercise price, high end of the range (in dollars per share)	$ 199.99
Number outstanding (in shares) | shares	502,416
Options outstanding, Weighted-average contractual life remaining	1 year
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 147.13
Options exercisable, Number exercisable (in shares) | shares	502,416
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 147.13
$200.00—$299.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, low end of the range (in dollars per share)	200.00
Exercise price, high end of the range (in dollars per share)	$ 299.99
Number outstanding (in shares) | shares	124,088
Options outstanding, Weighted-average contractual life remaining	1 month 6 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 240.28
Options exercisable, Number exercisable (in shares) | shares	124,088
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 240.28
$300.00—$399.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, low end of the range (in dollars per share)	300.00
Exercise price, high end of the range (in dollars per share)	$ 399.99
Number outstanding (in shares) | shares	200,000
Options outstanding, Weighted-average contractual life remaining	1 month 6 days
Options outstanding, Weighted-average exercise price (in dollars per share)	$ 335.50
Options exercisable, Number exercisable (in shares) | shares	200,000
Options exercisable, Weighted-average exercise price (in dollars per share)	$ 335.50