Debt Structure (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total Outstanding Debt	$ 4,557,184	$ 4,500,000
Debt Instrument, Interest Rate, Effective Percentage	3.40%	3.50%
Contract Maturity	Dec. 19, 2020
Variable Rate Debt [Member]
Debt Instrument [Line Items]
Unsecured Debt	$ 150,000
Secured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 1,296,498
Debt Instrument, Interest Rate, Effective Percentage	3.60%
Contract Maturity	Jun. 24, 2019
Secured Debt [Member] \| Mortgages [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Mortgage Loans on Real Estate	$ 1,109,438
Debt Instrument, Interest Rate, Effective Percentage	3.90%
Contract Maturity	Aug. 21, 2019
Secured Debt [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Total Outstanding Debt	$ 1,109,438
Debt Instrument, Interest Rate, Effective Percentage	3.90%
Contract Maturity	Aug. 21, 2019
Secured Debt [Member] \| Variable Rate Debt
Debt Instrument [Line Items]
Total Outstanding Debt	$ 160,000
Debt Instrument, Interest Rate, Effective Percentage	1.20%
Contract Maturity	Jun. 01, 2018
Secured Debt [Member] \| Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 160,000
Secured Debt [Member] \| Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] \| Variable Rate Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.20%
Contract Maturity	Jun. 01, 2018
Line of Credit Facility, Amount Outstanding	$ 160,000
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	1.20%
Secured Debt [Member] \| $750 million unsecured revolving credit facility [Member] \| Fair Market Value Adjustment and Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ (19,314)
Line of Credit Facility, Amount Outstanding	27,060
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 3,260,686
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Contract Maturity	Jul. 23, 2021
Unsecured Debt [Member] \| Wells Fargo Term Loan 2018 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250,000
Unsecured Debt [Member] \| Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
Unsecured Debt [Member] \| $500 million unsecured revolving credit faciltiy [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.88%
Unsecured Debt [Member] \| $500 million unsecured revolving credit faciltiy [Member] \| Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	1.90%
Contract Maturity	Apr. 15, 2020
Line of Credit Facility, Amount Outstanding	$ 570,000
Unsecured Debt [Member] \| $750 million unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 570,000
Unsecured Debt [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.10%
Contract Maturity	Nov. 10, 2017
Debt Instrument, Face Amount	$ 700,000
Unsecured Debt [Member] \| Senior Notes [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.10%
Contract Maturity	May 29, 2023
Debt Instrument, Face Amount	$ 1,860,000
Maximum [Member] \| Unsecured Debt [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Maturity Date, Description	6.2
Maximum [Member] \| Unsecured Debt [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Maturity Date, Description	P12Y
Maximum [Member] \| Unsecured Debt [Member] \| Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	190.00%
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%
Maximum [Member] \| Unsecured Debt [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	175.00%
Minimum [Member] \| Unsecured Debt [Member] \| Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Maturity Date, Description	P5Y
Minimum [Member] \| Unsecured Debt [Member] \| Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	90.00%
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] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

+ References

+ Details

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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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
Period Type:	instant

- Definition

Total carrying amount of mortgage loans as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule IV)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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Balance Type:	debit
Period Type:	instant

- Definition

Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: 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(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Subparagraph (SX 210.5-02(22))
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