Reportable Segments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Reconciliation of NOI
Rental income	$ 2,422,233	$ 2,736,578	$ 2,605,311
Property and maintenance expense	(406,823)	(479,160)	(473,098)
Real estate taxes and insurance expense	(317,387)	(339,802)	(325,401)
Total operating expenses	(724,210)	(818,962)	(798,499)
Net operating income	1,698,023	1,917,616	1,806,812
Rental income:
Rental Income - same store	2,177,304	2,099,166	2,441,390
Rental Income - non-same store	244,929	637,412	163,921
Rental Income	2,422,233	2,736,578	2,605,311
Operating expenses:
Operating Expenses - same store	634,120	613,924	744,096
Operating Expenses - non-same store	90,090	205,038	54,403
Total operating expenses	724,210	818,962	798,499
NOI:
NOI - same store	1,543,184	1,485,242	1,697,294
NOI - non-same store	154,839	432,374	109,518
Net operating income	$ 1,698,023	$ 1,917,616	$ 1,806,812
Units in same store properties	69,879	69,879	96,286
Total Assets	$ 20,704,148	$ 23,110,196
Capital Expenditures	172,177	182,113
Same store (1)
NOI:
Total Assets	16,648,892	17,105,124
Capital Expenditures	156,188	137,331
Non-same store/other (2) (3)
Rental income:
Rental Income - non-same store	163,768	72,123	$ 83,715
Operating expenses:
Operating Expenses - non-same store	56,403	27,078	28,992
NOI:
NOI - non-same store	107,365	45,045	54,723
Total Assets	2,864,250	2,441,637
Capital Expenditures	12,179	6,341
Los Angeles | Same store (1)
Rental income:
Rental Income - same store	368,734	349,285	259,437
Operating expenses:
Operating Expenses - same store	107,138	104,614	81,972
NOI:
NOI - same store	261,596	244,671	177,465
Total Assets	2,513,979	2,586,859
Capital Expenditures	26,195	22,015
San Diego | Same store (1)
Rental income:
Rental Income - same store	88,049	83,491	79,217
Operating expenses:
Operating Expenses - same store	23,489	22,938	22,605
NOI:
NOI - same store	64,560	60,553	56,612
Total Assets	471,937	488,260
Capital Expenditures	5,172	4,608
Orange County | Same store (1)
Rental income:
Rental Income - same store	79,602	75,068	71,440
Operating expenses:
Operating Expenses - same store	18,931	18,550	18,211
NOI:
NOI - same store	60,671	56,518	53,229
Total Assets	260,918	268,479
Capital Expenditures	6,747	7,336
Subtotal - Southern California | Same store (1)
Rental income:
Rental Income - same store	536,385	507,844	410,094
Operating expenses:
Operating Expenses - same store	149,558	146,102	122,788
NOI:
NOI - same store	386,827	361,742	287,306
Total Assets	3,246,834	3,343,598
Capital Expenditures	38,114	33,959
New York | Same store (1)
Rental income:
Rental Income - same store	457,882	450,460	455,598
Operating expenses:
Operating Expenses - same store	160,772	152,682	156,881
NOI:
NOI - same store	297,110	297,778	298,717
Total Assets	4,275,930	4,383,354
Capital Expenditures	25,329	18,170
Washington D.C. | Same store (1)
Rental income:
Rental Income - same store	424,055	417,985	451,973
Operating expenses:
Operating Expenses - same store	126,154	123,450	131,964
NOI:
NOI - same store	297,901	294,535	320,009
Total Assets	3,916,264	4,023,474
Capital Expenditures	33,867	33,455
San Francisco | Same store (1)
Rental income:
Rental Income - same store	365,019	343,089	340,252
Operating expenses:
Operating Expenses - same store	88,141	84,603	96,217
NOI:
NOI - same store	276,878	258,486	244,035
Total Assets	2,441,256	2,506,004
Capital Expenditures	24,411	25,104
Boston | Same store (1)
Rental income:
Rental Income - same store	237,683	232,462	244,612
Operating expenses:
Operating Expenses - same store	66,283	67,252	70,070
NOI:
NOI - same store	171,400	165,210	174,542
Total Assets	1,723,942	1,774,181
Capital Expenditures	20,936	17,355
Seattle | Same store (1)
Rental income:
Rental Income - same store	154,482	145,646	153,197
Operating expenses:
Operating Expenses - same store	42,644	39,307	45,781
NOI:
NOI - same store	111,838	106,339	107,416
Total Assets	1,031,764	1,061,351
Capital Expenditures	13,464	9,106
Other Markets | Same store (1)
Rental income:
Rental Income - same store	1,798	1,680	385,664
Operating expenses:
Operating Expenses - same store	568	528	120,395
NOI:
NOI - same store	1,230	1,152	265,269
Total Assets	12,902	13,162
Capital Expenditures	67	182
Other (3)
NOI:
Total Assets	1,191,006	3,563,435
Capital Expenditures	3,810	38,441
Other (3) | Non-same store/other (2) (3)
Rental income:
Rental Income - non-same store	81,161	565,289	80,206
Operating expenses:
Operating Expenses - non-same store	33,687	177,960	25,411
NOI:
NOI - non-same store	47,474	387,329	$ 54,795
Total Assets	4,055,256	6,005,072
Capital Expenditures	$ 15,989	$ 44,782