STOCKHOLDERS' EQUITY - Capital Stock (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019
Equity offering [Line Items]
Issuance of common stock	$ 98,438
At-The-Market Equity Offering Program
Equity offering [Line Items]
Common stock authorized under equity offering program		$ 1,000,000
Stock issued during period, shares, new issues, equity offering program		0.0
Equity offering program, remaining authorized offering amount		$ 822,100