Organization, Basis of Presentation, and Significant Accounting Policies Organization, Basis of Presentation, and Significant Accounting Policies (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ 1,861	$ 9,368	$ 0
Total real estate, net	15,942,309	14,935,740
Cash and cash equivalents	400,507	509,460	281,355	$ 2,733,618
Cash in escrow	104,821	95,625
Resident security deposits	30,077	29,617
Investments in unconsolidated real estate entities	216,919	298,315
Deferred development costs	37,577	67,029
Prepaid expenses and other assets	199,095	204,792
Total assets	16,931,305	16,140,578
Unsecured notes, net	3,845,674	2,975,533
Variable rate unsecured credit facility	0	0
Mortgage notes payable, net	2,611,274	3,514,174
Total liabilities	7,080,782	7,081,408
Redeemable noncontrolling interests	9,997	12,765
Total equity	9,840,526	9,046,405	$ 8,599,727	$ 6,840,793
Total liabilities and equity	16,931,305	16,140,578
New Debt Issuance Costs Guidance | Accounting Standard Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total real estate, net		14,935,740
Cash and cash equivalents		509,460
Cash in escrow		95,625
Resident security deposits		29,617
Investments in unconsolidated real estate entities		298,315
Deferred development costs		67,029
Prepaid expenses and other assets		204,792
Total assets		16,140,578
Unsecured notes, net		2,975,533
Variable rate unsecured credit facility		0
Mortgage notes payable, net		3,514,174
Other liabilities		591,701
Total liabilities		7,081,408
Redeemable noncontrolling interests		12,765
Total equity		9,046,405
Total liabilities and equity		16,140,578
Previously Reported | New Debt Issuance Costs Guidance | Accounting Standard Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total real estate, net		14,935,740
Cash and cash equivalents		509,460
Cash in escrow		95,625
Resident security deposits		29,617
Investments in unconsolidated real estate entities		298,315
Deferred development costs		67,029
Prepaid expenses and other assets		240,937
Total assets		16,176,723
Unsecured notes, net		2,993,265
Variable rate unsecured credit facility		0
Mortgage notes payable, net		3,532,587
Other liabilities		591,701
Total liabilities		7,117,553
Redeemable noncontrolling interests		12,765
Total equity		9,046,405
Total liabilities and equity		16,176,723
Restatement Adjustment | New Debt Issuance Costs Guidance | Accounting Standard Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total real estate, net		0
Cash and cash equivalents		0
Cash in escrow		0
Resident security deposits		0
Investments in unconsolidated real estate entities		0
Deferred development costs		0
Prepaid expenses and other assets		(36,145)
Total assets		(36,145)
Unsecured notes, net		(17,732)
Variable rate unsecured credit facility		0
Mortgage notes payable, net		(18,413)
Other liabilities		0
Total liabilities		(36,145)
Redeemable noncontrolling interests		0
Total equity		0
Total liabilities and equity		(36,145)
Unsecured notes
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred financing costs, net	21,725	17,732
Line of Credit [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred financing costs, net	2,148
Variable rate unsecured credit facility	0	0
Secured notes
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred financing costs, net	$ 14,703	$ 18,413