STOCK-BASED COMPENSATION, Equity Instruments Other Than Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock-based compensation, aggregate disclosures [Abstract]
Fair value of shares withheld for tax withholding obligations	$ 5,337	$ 2,844
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 32.94
Equity instruments other than options [Roll Forward]
Outstanding at January 1 (in shares)	213,113
Granted (in shares)	91,811
Vested (in shares)	(138,926)
Cancelled (in shares)	(1,324)
Outstanding at December 31 (in shares)	164,674	213,113
Equity instruments other than options, additional disclosures [Abstract]
Outstanding at January 1, Base price (in dollars per share)	$ 37.49
Vested, Base price (in dollars per share)	32.93
Cancelled, Base price (in dollars per share)	33.54
Outstanding at January 1, Base price (in dollars per share)	37.49
Stock-based compensation, aggregate disclosures [Abstract]
Weighted average grant-date fair value of restricted stock awards and units fully vested (in dollars per share)	$ 41.09	$ 37.95	$ 32.80
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 5,600	$ 3,100	$ 1,800
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Restricted stock awards and units vesting terms	1 year
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Restricted stock awards and units vesting terms	6 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 24.47
Equity instruments other than options [Roll Forward]
Outstanding at January 1 (in shares)	186,471
Granted (in shares)	770,205
Vested (in shares)	(169,352)
Cancelled (in shares)	0
Outstanding at December 31 (in shares)	787,324	186,471
Equity instruments other than options, additional disclosures [Abstract]
Outstanding at January 1, Base price (in dollars per share)	$ 43.43
Vested, Base price (in dollars per share)	22.82
Cancelled, Base price (in dollars per share)	0.00
Outstanding at January 1, Base price (in dollars per share)	43.43
Stock-based compensation, aggregate disclosures [Abstract]
Weighted average grant-date fair value of restricted stock awards and units fully vested (in dollars per share)	$ 43.49	$ 32.54	$ 32.54
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 7,300	$ 4,600	$ 5,700
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 33,200
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 11 months 16 days
Shares withheld for employee taxes (shares)	99,345	75,760	89,635
Shares withheld for employee taxes	$ 4,200	$ 2,600	$ 2,800
Performance Shares [Member]
Equity instruments other than options [Roll Forward]
Outstanding at January 1 (in shares)	71,868
Granted (in shares)	32,632	36,092
Vested (in shares)	(35,776)
Cancelled (in shares)	0
Outstanding at December 31 (in shares)	68,724	71,868
Equity instruments other than options, additional disclosures [Abstract]
Outstanding at January 1, Base price (in dollars per share)	$ 34.63	$ 39.42
Vested, Base price (in dollars per share)	32.56
Cancelled, Base price (in dollars per share)	0.00
Outstanding at January 1, Base price (in dollars per share)	34.63	39.42
Stock-based compensation, aggregate disclosures [Abstract]
Weighted average grant-date fair value of restricted stock awards and units fully vested (in dollars per share)	$ 35.98	$ 38.67	$ 40.17
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 1,500
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 7 days
Shares withheld for employee taxes (shares)	16,071
Shares withheld for employee taxes	$ 752
Performance-Based Vesting Requirement [Member] | Performance Shares [Member]
Equity instruments other than options [Roll Forward]
Granted (in shares)	16,315	18,044
Market-Based Vesting Requirement [Member] | Performance Shares [Member]
Equity instruments other than options [Roll Forward]
Granted (in shares)	16,317	18,048
Selling, General and Administrative Expenses [Member] | Restricted Stock Units (RSUs) [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	$ 6,000	$ 3,700	$ 3,800
Selling, General and Administrative Expenses [Member] | Performance Shares [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	871	1,400	453
Selling, General and Administrative Expenses [Member] | Director [Member] | Restricted Stock Units (RSUs) [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	865	797	525
Research and Development Expense [Member] | Restricted Stock Units (RSUs) [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	1,900	1,800	1,600
Research and Development Expense [Member] | Performance Shares [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	237	408	137
Research and Development Expense [Member] | Non Employee Members of Scientific Advisory Board [Member] | Restricted Stock [Member]
Stock-based compensation, aggregate disclosures [Abstract]
Compensation expense	$ 426	$ 175	$ 267