SUBSEQUENT EVENTS (Details)									3 Months Ended	12 Months Ended
	Apr. 15, 2020 USD ($) $ / shares	Feb. 28, 2020 USD ($) a	Feb. 21, 2020 USD ($) ft² a	Feb. 04, 2020 USD ($)	Jan. 29, 2020 $ / shares	Jan. 23, 2020 USD ($) ft²	Jan. 13, 2020 USD ($)	Mar. 11, 2015 USD ($) $ / shares	Dec. 31, 2017 $ / shares	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($)	Mar. 31, 2015 $ / shares
Subsequent Event [Line Items]
Square-Feet | ft²										502,626
Purchase price										$ 164,670,000
Face Amount of Mortgages										34,570,000
Face amount of debt										$ 288,729,722
4.50% Convertible Senior Notes due 2020
Subsequent Event [Line Items]
Stated interest rate (as a percent)										4.50%	4.50%
Face amount of debt								$ 75,000,000		$ 75,000,000
Outstanding amount										$ 74,706,078	$ 73,348,731
Conversion price per share								0.0145136	0.0145515
Conversion price per share | $ / shares								$ 68.90	$ 68.11			$ 68.11
Subsequent Event
Subsequent Event [Line Items]
Stated interest rate (as a percent)	3.875%
Subsequent Event | 4.50% Convertible Senior Notes due 2020
Subsequent Event [Line Items]
Stated interest rate (as a percent)				4.50%
Face amount of debt				$ 57,400,000
Proceeds from private placement				5,900,000
Repurchase of notes				5,900,000
Outstanding amount				$ 11,700,000
Subsequent Event | 3.875% Convertible Senior Notes due 2025
Subsequent Event [Line Items]
Stated interest rate (as a percent)				3.875%
Face amount of debt				$ 17,600,000
Proceeds from private placement				11,700,000
Outstanding amount				$ 75,000,000
Subsequent Event | 2025 Notes maturing on April 15, 2025
Subsequent Event [Line Items]
Conversion price per share	12.7910
Threshold principal amount for adjusted conversion price	$ 1,000
Conversion price per share | $ / shares	$ 78.18
Premium initial conversion price					20.00%
Closing share price (in dollars per share) | $ / shares					$ 65.15
Subsequent Event | Crossroads
Subsequent Event [Line Items]
Square-Feet | ft²						254,000
Purchase price						$ 61,800,000
Subsequent Event | Perimeter
Subsequent Event [Line Items]
Square-Feet | ft²			269,000
Purchase price			$ 75,400,000
Area of land (in acres) | a			24
Remaining proceeds from sale of properties			$ 65,000,000
Subsequent Event | First Mortgage, Redevelopment Property Honolulu, Hawaii
Subsequent Event [Line Items]
Face Amount of Mortgages							$ 3,500,000
Term							1 year
Interest rate (as a percent)							11.00%
Origination fee (as a percent)							2.00%
Origination fee received							$ 70,000
Subsequent Event | First Mortgage, Land JV
Subsequent Event [Line Items]
Area of land (in acres) | a		12
Face Amount of Mortgages		$ 3,400,000
Term		1 year
Interest rate (as a percent)		9.50%
Origination fee (as a percent)		1.50%
Origination fee received		$ 51,000