Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 56,675	$ 56,237	$ 55,907	$ 58,466	$ 54,201	$ 53,233	$ 52,710	$ 56,926	$ 227,285	$ 217,070	$ 209,077
Expenses									(55,592)	(53,701)	(51,143)
Income from real estate									171,693	163,369	157,934
Interest expense and amortization of deferred debt costs									(47,225)	(45,683)	(45,165)
General and administrative									(18,176)	(17,496)	(16,353)
Subtotal									106,292	100,190	96,416
Depreciation and amortization of deferred leasing costs									(45,694)	(44,417)	(43,270)
Acquisition related costs									0	(60)	(84)
Predevelopment expenses									0	0	(132)
Change in fair value of derivatives									70	(6)	(10)
Gain on sale of property	0	$ 0	$ 0	$ 0	1,013	$ 0	$ 0	$ 0	0	1,013	11
Net income (loss)									60,668	56,720	52,931
Capital investment									119,994	91,045	69,619
Total assets	1,422,452				1,343,025				1,422,452	1,343,025	1,295,408
Operating Segments | Shopping Centers
Segment Reporting Information [Line Items]
Revenue									165,853	160,179	156,110
Expenses									(34,675)	(34,931)	(33,877)
Income from real estate									131,178	125,248	122,233
Interest expense and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Subtotal									131,178	125,248	122,233
Depreciation and amortization of deferred leasing costs									(29,977)	(29,964)	(30,171)
Acquisition related costs										(60)	(84)
Predevelopment expenses											(57)
Change in fair value of derivatives									0	0	0
Gain on sale of property										0	11
Net income (loss)									101,201	95,224	91,932
Capital investment									90,896	64,044	17,159
Total assets	974,061				976,545				974,061	976,545	931,256
Operating Segments | Mixed-Use Properties
Segment Reporting Information [Line Items]
Revenue									61,352	56,840	52,916
Expenses									(20,917)	(18,770)	(17,266)
Income from real estate									40,435	38,070	35,650
Interest expense and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Subtotal									40,435	38,070	35,650
Depreciation and amortization of deferred leasing costs									(15,717)	(14,453)	(13,099)
Acquisition related costs										0	0
Predevelopment expenses											(75)
Change in fair value of derivatives									0	0	0
Gain on sale of property										1,013	0
Net income (loss)									24,718	24,630	22,476
Capital investment									29,098	27,001	52,460
Total assets	438,283				358,419				438,283	358,419	354,254
Corporate
Segment Reporting Information [Line Items]
Revenue									80	51	51
Expenses									0	0	0
Income from real estate									80	51	51
Interest expense and amortization of deferred debt costs									(47,225)	(45,683)	(45,165)
General and administrative									(18,176)	(17,496)	(16,353)
Subtotal									(65,321)	(63,128)	(61,467)
Depreciation and amortization of deferred leasing costs									0	0	0
Acquisition related costs										0	0
Predevelopment expenses											0
Change in fair value of derivatives									70	(6)	(10)
Gain on sale of property										0	0
Net income (loss)									(65,251)	(63,134)	(61,477)
Capital investment									0	0	0
Total assets	$ 10,108				$ 8,061				$ 10,108	$ 8,061	$ 9,898