Component of Rental Income and Expense Components of Rental Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Rental Income [Line Items]
Cost reimbursement	$ 29,052	$ 27,583	$ 27,763
Percentage rent	3,107	2,655	2,608
Hotel revenue	33,911	35,137	31,729
Other	1,681	1,688	1,597
Total rental income	246,078	242,757	225,249
Total Retail
Rental Income [Line Items]
Minimum rents	70,573	69,374	67,046
Total Office
Rental Income [Line Items]
Minimum rents	82,018	81,845	71,817
Total Multifamily
Rental Income [Line Items]
Minimum rents	15,732	14,926	13,796
Total Mixed-Use
Rental Income [Line Items]
Minimum rents	$ 10,004	$ 9,549	$ 8,893