Accounts payable, accrued expenses, and tenant security deposits (Notes)

12 Months Ended

Dec. 31, 2013

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 December 31, 2013 and 2012 (in thousands):



	December 31,
	2013		2012
Accounts payable and accrued expenses	$	98,037	$	105,520
Accrued construction	78,098		83,104
Acquired below market leases	11,405		14,721
Conditional asset retirement obligations	7,386		9,240
Deferred rent liability	35,134		34,414
Interest rate swap liabilities	6,191		20,661
Prepaid rent and tenant security deposits	188,241		143,878
Other liabilities	10,850		12,170
Total	$	435,342	$	423,708

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. In addition, for certain properties, we have not recognized 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.