CAPITAL STOCK - NARRATIVE (Details) $ / shares in Units, $ in Thousands					1 Months Ended				12 Months Ended
	Mar. 05, 2021 USD ($) $ / shares shares	Apr. 14, 2020 shares	Apr. 01, 2020 USD ($)	Mar. 30, 2020 USD ($) $ / shares shares	Apr. 30, 2020 shares	May 31, 2018 shares	May 31, 2016 shares	May 31, 2012 shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	May 31, 2003 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend rate (as a percent)									0.00%	0.00%	0.00%
Reverse stock split conversion ratio									10
Fair value of stock options granted during period									$ 1,600	$ 2,400	$ 2,600
Weighted average grant date fair value | $ / shares									$ 82.77	$ 28.66	$ 29.89
Intrinsic value of options exercised									$ 9,900	$ 5,000	$ 12,800
Proceeds from stock options exercised									3,300	$ 3,400	$ 1,000
Unrecognized compensation costs, not probable									$ 30,900
Weighted average purchase price of shares purchased | $ / shares									$ 29.56	$ 16.19	$ 18.10
Preferred stock, shares issued (in shares) | shares									0	0
Preferred stock, par value (in dollars per share) | $ / shares									$ 0.01	$ 0.01
Payments of stock issuance costs									$ 314	$ 214	$ 0
Risk-free interest rate (as a percent)									0.98%	3.64%	1.62%
Expected volatility (as a percent)									47.00%	46.00%	40.00%
Equity Offering, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, price per share (in dollars per share) | $ / shares	$ 186.00
Sale of stock, number of shares issued in transaction (in shares) | shares	940,860
Common stock, par value (in dollars per share) | $ / shares	$ 0.01
Sale of stock, conversion received on transaction	$ 164,200
Over-Allotment Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, price per share (in dollars per share) | $ / shares	$ 186.00
Authorized shares (in shares) | shares	141,129
Over allotment option period	30 days
Series X Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion to common stock (in shares) | shares		122,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued | shares									0	0
Conversion to common stock (in shares) | shares		1,508,964
Common stock, par value (in dollars per share) | $ / shares									$ 0.01	$ 0.01
Scil Animal Care Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price in cash			$ 110,300	$ 111,000
Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares issued (in shares) | shares				122,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.01
Sale of stock, price per share (in dollars per share) | $ / shares				$ 1,000
Sale of stock, consideration received per transaction				$ 122,000
Payments of stock issuance costs				$ 200
Convertible preferred stock, shares issuable upon conversion (in shares)				12.4
Preferred stock, convertible, conversion price (in dollars per share) | $ / shares				$ 80.85
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount									$ 22,200
Weighted average purchase price of shares purchased | $ / shares									$ 207.24
Share-based Compensation Arrangement by Share-based Payment Award, Weighted Average Award Vesting Period									1 year 4 months 24 days
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)									1 year
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)									7 years
Stock options and restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised									$ 42,100
Total unrecognized compensation expense related to outstanding stock options									$ 2,900
Period for recognition of unrecognized compensation expense									1 year 3 months 21 days
Intrinsic value of options outstanding									$ 49,900
Granted at Market (in dollars per share) | $ / shares									$ 188.62
Forfeitures in period (in shares) | shares									71
Options outstanding (in shares) | shares									420,202	464,232
Weighted Average Outstanding Price (in dollars per share) | $ / shares									$ 64.06	$ 57.18
Exercises in period (in shares) | shares									63,459
Incentive Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of fair value for options granted									100.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock options granted during period									$ 2,600	$ 6,000	$ 0
Weighted average grant date fair value | $ / shares									$ 75.62	$ 0
Intrinsic value of options exercised									$ 26,700
Proceeds from stock options exercised									3,000
Total unrecognized compensation expense related to outstanding stock options									$ 2,800
Period for recognition of unrecognized compensation expense									1 year
Performance shares not meeting performance targets (in shares) | shares									45,000
Unrecognized compensation costs, not probable									$ 1,100
Weighted average purchase price of shares purchased | $ / shares									$ 198.40
Risk-free interest rate (as a percent)									0.77%
Expected volatility (as a percent)									46.30%
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period | shares									5,437	10,069	10,698
Share Purchase Plan 1997
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of share to be repurchased | shares					300,000	250,000	500,000	250,000
Number of shares authorized to be repurchased annually | shares								45,000
Remaining number of shares authorized to be repurchased | shares									109,301
Common stock, shares issued | shares									9,296
Share Purchase Plan 2003
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of share to be repurchased | shares								250,000
Number of shares authorized | shares												239,050
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount									$ 600
Shares not meeting performance targets | shares									191,000
Weighted average purchase price of shares purchased | $ / shares									$ 172.11	$ 87.29	$ 74.93
Restricted stock vested, fair value									$ 5,600	$ 5,000	$ 300
Share-based Compensation Arrangement by Share-based Payment Award, Weighted Average Award Vesting Period									1 year 7 months 6 days