Investments in Unconsolidated Real Estate Entities - Schedule of Operation for Apartment LLCs (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Rental									$ 360,615	$ 355,583	$ 341,902
Other property revenues									22,182	21,237	19,963
Total revenues	$ 97,377	$ 97,767	$ 95,431	$ 93,431	$ 92,813	$ 96,461	$ 95,026	$ 93,512	384,006	377,812	362,737
Expenses
Property operating and maintenance									165,356	162,959	155,261
Interest									31,587	40,286	44,704
Total expenses									272,507	271,016	263,610
Net income available to the Company									80,623	215,120	110,534
Company's share of net income in Apartment LLCs									2,208	1,788	2,090
Unconsolidated Properties [Member]
Revenues
Rental									27,795	26,502	25,692
Other property revenues									1,952	1,857	1,881
Total revenues									29,747	28,359	27,573
Expenses
Property operating and maintenance									11,918	11,939	10,955
Depreciation and amortization									5,886	5,608	5,421
Interest									9,052	9,052	9,052
Total expenses									26,856	26,599	25,428
Net income available to the Company									2,891	1,760	2,145
Company's share of net income in Apartment LLCs									$ 2,208	$ 1,788	$ 2,090