Accounts payable, accrued expenses, and tenant security deposits

3 Months Ended

Mar. 31, 2018

Accounts payable, accrued expenses, and tenant security deposits [Abstract]

Accounts payable, accrued expenses, and tenant security deposits

The following table summarizes the components of accounts payable, accrued expenses, and tenant security deposits as of March 31, 2018, and December 31, 2017 (in thousands):



	March 31, 2018		December 31, 2017
Accounts payable and accrued expenses	$	370,183	$	349,884
Acquired below-market leases	85,101		88,184
Conditional asset retirement obligations	6,997		7,397
Deferred rent liabilities	28,121		27,953
Interest rate hedge liabilities	—		103
Unearned rent and tenant security deposits	252,259		248,924
Other liabilities	41,325		41,387
Total	$	783,986	$	763,832

Some of our properties may contain asbestos, which, under certain conditions, requires remediation. Although we believe that the asbestos is appropriately contained in accordance with environmental regulations, our practice is to remediate the asbestos upon the development or redevelopment of the affected property. We recognize a liability for the fair value of a conditional asset retirement obligation (including asbestos) when the fair value of the liability can be reasonably estimated. For certain properties we do not recognize an asset retirement obligation when there is an indeterminate settlement date for the obligation because the period in which we may remediate the obligation may not be estimated with any level of precision to provide for a meaningful estimate of the retirement obligation.