SHAREHOLDERS' INTEREST - Reconciliation of Our Common Share Activity (Details) - shares		12 Months Ended
	Jul. 01, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Outstanding at beginning of year		755,222,727	748,528,000	510,483,000
Preference shares converted to common shares	23,200,000	0	0	23,345,000
Repurchased		(11,410,000)	0	(67,817,000)
Outstanding at end of year		746,390,932	755,222,727	748,528,000
Stock options
Class of Stock [Line Items]
Stock options exercised		2,026,000	5,970,000	2,571,000
Restricted stock units
Class of Stock [Line Items]
Stock options exercised		466,000	605,000	840,000
Performance share units
Class of Stock [Line Items]
Stock options exercised		86,000	120,000	219,000
Plum Creek
Class of Stock [Line Items]
Issuance from merger with Plum Creek (Note 5)		0	0	278,887,000