CAPITAL STOCK - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended			67 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options and restricted stock, anti-dilutive (in shares)				5,000,000.0	5,600,000	7,300,000
Common stock share purchase, shares (in shares)				40,000,000				40,000,000	40,000,000
Treasury shares acquired (in shares)				0	7,827,333	0	40,000,000
Common stock share repurchase price (in USD per share)							$ 79.18
Common stock dividends (in USD per share)				$ 1.00	$ 1.00	$ 1.00
Shares authorized and available for grant (in shares)				14,400,000
Shares Issued in the period (in shares)				0
Shares exercised in the period (in shares)				0	(29,000)	(15,000)
Intrinsic value of options exercised				$ 0.1	$ 0.2
Stock-settled and cash-settled compensation expensed				110.0	157.0	$ 142.0
Stock-settled and cash-settled compensation capitalized				28.0	37.0	41.0
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized				2.0
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized				18.0
Stock-settled and cash-settled compensation expensed				$ 104.0	$ 101.0	$ 108.0
Awards granted during period (in shares)				1,479,000	608,000	1,948,000
Weighted average grant date fair value per share (in USD per share)				$ 36.81	$ 45.59	$ 62.74
Stock-settled and cash-settled compensation capitalized				$ 24.0	$ 29.0	$ 35.0
Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized				$ 52.0
Awards granted during period (in shares)				4,831,000	1,973,000
Subsequent Event | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period in which stock options become exercisable	3 years
Total compensation cost related to non-vested awards not yet recognized	$ 25.0
Awards granted during period (in shares)	961,368
Weighted average grant date fair value per share (in USD per share)	$ 25.69
Subsequent Event | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized	$ 86.0
Awards granted during period (in shares)	3,340,495
Prior to 2016 | Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period in which stock options become exercisable				4 years
Period in which stock options expires after grant date				10 years
In or after 2016 | Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period in which stock options become exercisable				3 years
Period in which stock options expires after grant date				10 years
ALTM | Subsequent Event | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per share (in USD per share)	$ 2.70
ALTM | Subsequent Event | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized	$ 4.0
Awards granted during period (in shares)	1,425,513
2018 Performance Program | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during period (in shares)			931,049
2019 Performance Program | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during period (in shares)		1,679,832