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Notes Payable - Additional Information (Detail) - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2016 | Dec. 31, 2015
Debt Instrument [Line Items] |  |
Notes Payable | $ 3,489,425 | $ 3,430,000
Debt Instrument, Interest Rate, Effective Percentage | 3.70% | 3.70%
Conventional Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate | 1.10% |
Long-term Debt | $ 115,000 |
Capped Conventional Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate | 1.10% |
Long-term Debt | $ 75,000 |
Mortgages [Member] |  |
Debt Instrument [Line Items] |  |
Repayments of Notes Payable | 3,600 |
Other Than Conventional Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt | $ 1,000,000 |
Debt Instrument Average Interest Rate | 4.00% |
Fixed Rate Senior Notes [Member] |  |
Debt Instrument [Line Items] |  |
Unsecured notes payable | $ 2,100,000 |
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate | 3.90% |
Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Notes Payable | $ 1,243,198 |
Debt Instrument, Interest Rate, Effective Percentage | 3.60% |
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 0.17% |
Line of Credit Facility, Commitment Fee Percentage | 0.62% |
Line of Credit Facility, Amount Outstanding | $ 240,000 |
Line of Credit Facility, Maximum Borrowing Capacity | $ 240,000 |
Debt Renewal Period | 90 days |
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Effective Percentage | 1.10% |
Line of Credit Facility, Amount Outstanding | $ 190,000 |
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Effective Percentage | 4.70% |
Line of Credit Facility, Amount Outstanding | $ 50,000 |
Secured Debt [Member] | Mortgages [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Effective Percentage | 4.00% |
Mortgage Loans on Real Estate | $ 975,330 |
Unsecured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Notes Payable | $ 2,246,227 |
Debt Instrument, Interest Rate, Effective Percentage | 3.70% |
Unsecured Debt [Member] | Wells Fargo Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | $ 250,000 |
Unsecured Debt [Member] | US Bank Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | $ 150,000 |
Unsecured Debt [Member] | $500 million unsecured revolving credit faciltiy [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Effective Percentage | 1.47% |
Letters of Credit Outstanding, Amount | $ 2,800 |
Unsecured Debt [Member] | $500 million unsecured revolving credit faciltiy [Member] | Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Effective Percentage | 1.50% |
Line of Credit Facility, Amount Outstanding | $ 180,000 |
Unsecured Debt [Member] | KeyBank Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | 150,000 |
Unsecured Debt [Member] | Public Income Notes [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | 1,200,000 |
Unsecured Debt [Member] | Private Placement [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | 310,000 |
Unsecured Debt [Member] | 2011 and 2012 Senior Notes [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | 310,000 |
Unsecured Debt [Member] | $750 million unsecured revolving credit facility [Member] |  |
Debt Instrument [Line Items] |  |
Line of Credit Facility, Amount Outstanding | 180,000 |
Line of Credit Facility, Maximum Borrowing Capacity | 750,000 |
Unsecured Debt [Member] | Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Face Amount | $ 550,000 |
Debt Instrument, Interest Rate, Effective Percentage | 3.10% |
Minimum [Member] | Unsecured Debt [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Maturity Date, Description | P5Y |
Minimum [Member] | Unsecured Debt [Member] | $500 million unsecured revolving credit faciltiy [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 0.85% |
Minimum [Member] | Unsecured Debt [Member] | KeyBank Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 0.90% |
Minimum [Member] | Unsecured Debt [Member] | Wells Fargo and US Bank Term Loans [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 0.90% |
Maximum [Member] | Unsecured Debt [Member] | Fixed Rate Debt |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Maturity Date, Description | P12Y |
Maximum [Member] | Unsecured Debt [Member] | $500 million unsecured revolving credit faciltiy [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 1.55% |
Line of Credit Facility, Maximum Borrowing Capacity | $ 1,500,000 |
Maximum [Member] | Unsecured Debt [Member] | KeyBank Term Loan [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 1.75% |
Maximum [Member] | Unsecured Debt [Member] | Wells Fargo and US Bank Term Loans [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Basis Spread on Variable Rate | 1.90% |
Farmington Village [Member] | Secured Debt [Member] | Mortgages [Member] | Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Repayments of Debt | $ 13,400 |
Colonial Grand at Wilmington [Member] | Secured Debt [Member] | Mortgages [Member] | Variable Rate Debt [Member] |  |
Debt Instrument [Line Items] |  |
Repayments of Debt | $ 20,200 |

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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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