Accounts payable, accrued expenses, and tenant security deposits

9 Months Ended

Sep. 30, 2017

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 September 30, 2017, and December 31, 2016 (in thousands):



	September 30, 2017		December 31, 2016
Accounts payable and accrued expenses	$	338,296	$	366,174
Acquired below-market leases	92,388		59,509
Conditional asset retirement obligations	7,457		3,095
Deferred rent liabilities	27,747		34,426
Interest rate hedge liabilities	583		3,587
Unearned rent and tenant security deposits	240,501		231,416
Other liabilities	33,098		33,464
Total	$	740,070	$	731,671

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. These conditional asset retirement obligations are included in the table above.