Commitments and Contingencies:

12 Months Ended

Dec. 31, 2012

Commitments and Contingencies:

Commitments and Contingencies:

18. Commitments and Contingencies:

        The Company has certain properties subject to non-cancelable operating ground leases. The leases expire at various times through 2098, subject in some cases to options to extend the terms of the lease. Certain leases provide for contingent rent payments based on a percentage of base rental income, as defined in the lease. Ground rent expenses were $8,681, $8,607 and $6,494 for the years ended December 31, 2012, 2011 and 2010, respectively. No contingent rent was incurred for the years ended December 31, 2012, 2011 or 2010.

        Minimum future rental payments required under the leases are as follows:

Year Ending December 31,
2013	$	14,496
2014		13,315
2015		12,173
2016		12,201
2017		12,186
Thereafter		276,176
	$	340,547

        As of December 31, 2012, the Company was contingently liable for $3,757 in letters of credit guaranteeing performance by the Company of certain obligations relating to the Centers. The Company does not believe that these letters of credit will result in a liability to the Company.

        The Company has entered into a number of construction agreements related to its redevelopment and development activities. Obligations under these agreements are contingent upon the completion of the services within the guidelines specified in the agreement. At December 31, 2012, the Company had $41,107 in outstanding obligations, which it believes will be settled in the next twelve months.