RECENT TRANSACTIONS (Details)										9 Months Ended
	Sep. 25, 2018 USD ($)	Sep. 21, 2018	Sep. 19, 2018 USD ($) a	Sep. 18, 2018 USD ($)	Sep. 07, 2018 USD ($) ft² a building	Jul. 10, 2018 USD ($) a	Jun. 08, 2018 USD ($) a extention_option	Apr. 30, 2018 USD ($) extention_option	Feb. 23, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Debt Instrument [Line Items]
Area of land sold (in acres) | a			38			123
Sales price of land			$ 22,100,000			$ 69,000,000
Number of buildings acquired | building					2
Square footage of buildings acquired | ft²					257,025
Acreage of real estate acquired | a					12.9
Payments to acquire real estate					$ 53,000,000
Notes receivable, net						$ 35,800,000				$ 40,220,000	$ 5,864,000
Repurchase of common shares (in shares) | shares									475,920
Common stock, par value (in dollars per share) | $ / shares									$ 0.01	$ 0.01	$ 0.01
Repurchase price per share (in dollars per share) | $ / shares									$ 120.33
Repurchase of common shares									$ 57,300,000	$ 57,267,000
250 Water Street
Debt Instrument [Line Items]
Area of land purchased | a							1
Purchase price of land acquired							$ 180,000,000
Payments to acquire land							53,100,000
Wacker110 N | Construction Loans
Debt Instrument [Line Items]
Loan amount	$ 512,600,000.0							$ 494,500,000.0
Number of extension options | extention_option								2
Term of extension option								1 year
Joint venture debt guaranteed								$ 89,000,000
Increase in joint venture debt guaranteed	$ 92,300,000
London Interbank Offered Rate (LIBOR) | Construction Loans
Debt Instrument [Line Items]
Interest rate margin (as a percent)				1.65%
London Interbank Offered Rate (LIBOR) | Wacker110 N | Construction Loans
Debt Instrument [Line Items]
Interest rate margin (as a percent)								3.00%
Notes Payable, Other Payables | 250 Water Street
Debt Instrument [Line Items]
Note payable to acquire land							$ 129,700,000
Interest free term							6 months
Number of extension options | extention_option							3
Term of extension option							6 months
Interest rate (as a percent)							6.00%
Minimum paydown for term extension							$ 30,000,000
$700 Million Loan Maturity September 2023
Debt Instrument [Line Items]
Loan amount				$ 700,000,000.0
Option to increase borrowing capacity				50,000,000.0
Percent of loan covered by derivative		100.00%
Derivative fixed interest rate		4.61%
$700 Million Loan Maturity September 2023 | Term Loan
Debt Instrument [Line Items]
Loan amount				615,000,000
Revolving Credit Facility | $700 Million Loan Maturity September 2023 | Line of Credit
Debt Instrument [Line Items]
Loan amount				$ 85,000,000.0