Accounts payable, accrued expenses, and tenant security deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts payable, accrued expenses, and tenant security deposits [Abstract]
Accounts payable and accrued expenses	$ 370,183	$ 349,884
Acquired below market leases	85,101	88,184
Asset Retirement Obligation	6,997	7,397
Deferred Rent Liability	28,121	27,953
Interest rate hedge liabilities	0	103
Prepaid Rent and Tenant Security Deposits	252,259	248,924
Other Accounts Payable and Accrued Liabilities	41,325	41,387
Accounts Payable and Accrued Liabilities	$ 783,986	$ 763,832