SHARE-BASED AWARDS - SUMMARY (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) plan $ / shares shares
Stock options
Activity in the entity's stock option plans
Outstanding, beginning of period (in shares)	324
Exercised (in shares)	(87)
Forfeited and expired (in shares)	(2)
Outstanding, end of period (in shares)	235
Exercisable, end of period (in shares)	235
Weighted average exercise price
Outstanding, weighted average exercise price, beginning of period (in dollars per share) | $ / shares	$ 21.67
Exercised, weighted average exercise price (in dollars per share) | $ / shares	21.95
Forfeited and expired, weighted average exercise price (in dollars per share) | $ / shares	24.72
Outstanding, weighted average exercise price, end of period (in dollars per share) | $ / shares	21.54
Exercisable, weighted average exercise price, end of period (in dollars per share) | $ / shares	$ 21.54
Outstanding, weighted average contractual life, end of period	3 years 3 months 18 days
Exercisable, weighted average contractual life, end of period	3 years 3 months 18 days
Outstanding, aggregate intrinsic value, end of period (in dollars) | $	$ 1,946
Exercisable, aggregate intrinsic value, end of period (in dollars) | $	$ 1,946
Restricted Stock Units
Share-based compensation
Options granted, weighted average grant-date fair value (in dollars per share) | $ / shares	$ 31.76
2016 Plan
Share-based compensation
Common stock initially available for future issuance (in shares)	2,500
Number of separate incentive compensation programs | plan	4
Number of share based compensation plans within the entity's incentive compensation programs | plan	3
2007 Plan | Discretionary Grant Program
Share-based compensation
Minimum exercise price as a percentage of fair market value of common stock	100.00%
Exercisable period	3 years
Expiration Term	10 years
2007 Plan | Stock options
Activity in the entity's stock option plans
Outstanding, beginning of period (in shares)	319
Exercised (in shares)	(84)
Outstanding, end of period (in shares)	235
Exercisable, end of period (in shares)	235
2007 Plan | Time-Based Restricted Stock Units | Stock Issuance Program
Share-based compensation
Vesting period of awards granted	3 years
2007 Plan | Performance-Based Restricted Stock Units | Stock Issuance Program
Share-based compensation
Vesting period of awards granted	3 years
1998 Plan | Stock options
Activity in the entity's stock option plans
Outstanding, beginning of period (in shares)	5
Exercised (in shares)	(3)
Forfeited and expired (in shares)	(2)