CAPITAL STOCK AND SHARE-BASED COMPENSATION - Employee Stock Purchase Plan Purchases (Details) - $ / shares	3 Months Ended								79 Months Ended	103 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Employee Stock Purchase Plan shares issued (shares)	4,202	4,789	5,414	5,295	6,063	7,216	8,230	7,181	3,122,983	3,171,373
Price per Employee Stock Purchase Plan share issued (usd per share)	$ 249.33	$ 200.97	$ 168.76	$ 156.01	$ 141.88	$ 111.36	$ 103.20	$ 104.77	$ 15.92	$ 249.33