Investments in Unconsolidated Real Estate Entities - Schedule of Operation for Apartment LLCs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues
Rental	$ 90,751	$ 87,895	$ 268,193	$ 253,174
Other property revenues	5,476	5,274	16,130	15,190
Total revenues	96,461	93,394	284,999	269,032
Expenses
Property operating and maintenance	41,675	40,266	124,066	115,723
Interest	9,858	11,186	31,535	33,280
Total expenses	68,600	68,691	205,178	196,579
Net income available	133,706	18,973	195,661	66,803
Company's share of net income in Apartment LLCs	422	656	1,408	1,611
Unconsolidated Properties [Member]
Revenues
Rental	6,701	6,505	19,821	19,141
Other property revenues	481	475	1,410	1,435
Total revenues	7,182	6,980	21,231	20,576
Expenses
Property operating and maintenance	3,167	2,550	8,749	7,939
Depreciation and amortization	1,412	1,362	4,175	4,052
Interest	2,278	2,278	6,774	6,774
Total expenses	6,857	6,190	19,698	18,765
Net income available	325	790	1,533	1,811
Company's share of net income in Apartment LLCs	$ 422	$ 656	$ 1,408	$ 1,611