SHAREHOLDERS' INTEREST - Reconciliation of Our Common Share Activity (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Outstanding at beginning of year	745,300	746,391	755,223
Repurchased	0	(2,349)	(11,410)
Outstanding at end of year	747,385	745,300	746,391
Stock options
Class Of Stock [Line Items]
Stock issued under share-based payment arrangement	1,441	660	2,026
Vested restricted stock units
Class Of Stock [Line Items]
Stock issued under share-based payment arrangement	574	480	466
Vested performance share units
Class Of Stock [Line Items]
Stock issued under share-based payment arrangement	70	118	86