Segment Reporting Operating Activity Within Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating income (loss)	$ 22,526	$ 23,036	$ 17,726	$ 20,381	$ 20,407	$ 21,441	$ 19,373	$ 19,880	$ 83,669	$ 81,101	$ 71,906
Gross Profit									168,769	165,071	149,352
Total Retail
Segment Reporting Information [Line Items]
Property revenue									96,140	93,449	91,991
Property expense									(25,451)	(23,900)	(24,955)
Operating income (loss)									70,689	69,549	67,036
Total Office
Segment Reporting Information [Line Items]
Property revenue									92,474	90,527	78,101
Property expense									(27,003)	(26,688)	(23,780)
Operating income (loss)									65,471	63,839	54,321
Total Multifamily
Segment Reporting Information [Line Items]
Property revenue									16,976	16,125	14,852
Property expense									(6,099)	(5,917)	(5,914)
Operating income (loss)									10,877	10,208	8,938
Total Mixed-Use
Segment Reporting Information [Line Items]
Property revenue									54,410	54,956	50,522
Property expense									(32,678)	(33,481)	(31,465)
Operating income (loss)									$ 21,732	$ 21,475	$ 19,057