COMMON SHARES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended
	Mar. 26, 2020	Mar. 23, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Equity offering (in shares)			6,000,000	5,980,000
Common shares issuable pursuant to forward sale agreement (in shares)	4,460,000	1,500,000		11,960,000
Net proceeds from common shares issued directly by the Company	$ 314,100	$ 105,700			$ 419,786	$ 0
Forward sale price (in dollars per share)	$ 71.48
Common shares issued directly by the Company (in shares)					5,960,000
Treasury stock (in shares)			15,977,757		15,407,215
Common stock outstanding (in shares)			329,880,645		336,411,187