SHAREHOLDERS' INTEREST - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 07, 2019
Class Of Stock [Line Items]
Shares repurchased during period	0	2,349,000	11,410,000
Shares repurchased during period value	$ 0	$ 60,000,000	$ 366,000,000
Unsettled share repurchases	$ 0	$ 0
2019 Repurchase Program
Class Of Stock [Line Items]
Stock repurchase program, authorized amount				$ 500,000,000
Shares repurchased during period	0	2,300,000
Shares repurchased during period value		$ 60,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 440,000,000	$ 440,000,000
2016 Repurchase Program
Class Of Stock [Line Items]
Shares repurchased during period			11,400,000
Shares repurchased during period value			$ 366,000,000
Stock repurchase program, remaining authorized repurchase amount			$ 135,000,000
Preferred shares
Class Of Stock [Line Items]
Preferred shares, outstanding	0	0
Preferred shares, authorized	7,000,000	40,000,000
Preferred shares, par value	$ 1.00	$ 1.00