CAPITAL STOCK - Completed public offerings ofcommon stock (Details) - USD ($)	3 Months Ended			12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Issued During Period Shares New Issues				14,377,000		20,045,000
Stock Issued During Period, Value, New Issues				$ 92,314,000		$ 197,607,000
At the Market Offering Program [Member]
Weighted Average Price Received Per Share	$ 6.37	$ 6.7	$ 6.84
Stock Issued During Period Shares New Issues	1,771,301	4,337,931	1,267,894		14,377,126
Stock Issued During Period, Value, New Issues	$ 11,098,000	$ 28,495,000	$ 8,503,000		$ 92,314,000
Follow-on Offering [Member]
Weighted Average Price Received Per Share	$ 6.35
Stock Issued During Period Shares New Issues	7,000,000
Stock Issued During Period, Value, New Issues	$ 44,218,000