COMMON SHARES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Dec. 30, 2019	Jun. 04, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Equity offering (in shares)		17,940,000
Common shares issued directly by the Company (in shares)		5,980,000	11,980,000
Common shares issuable pursuant to forward sale agreement (in shares)	6,000,000	11,960,000
Net proceeds from common shares issued directly by the Company	$ 425,400	$ 426,900	$ 852,254	$ 0	$ 0
Forward sale price (in dollars per share)	$ 71.48
Amount that would have been required to be paid if net settled			$ 84,400
Shares that would have been required to be delivered if net settled (in shares)			992,189
Treasury stock (in shares)			15,977,757	16,992,594
Common stock outstanding (in shares)			329,880,645	316,885,808