Notes and Contracts Payable (Schedule of Notes and Contracts Payable) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Credit facility interest rate	3.30%
Weighted-average interest rate	4.22%	4.42%
Senior Notes \| 4.60% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes maturity date	Nov. 15, 2024
Effective interest rate	4.60%
Senior Notes \| 4.30% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes maturity date	Feb. 01, 2023
Effective interest rate	4.35%
Line of Credit \| 3.30% interest rate
Debt Instrument [Line Items]
Credit agreement termination date	Apr. 30, 2024
Credit facility interest rate	3.30%
Line of Credit \| 4.15% interest rate
Debt Instrument [Line Items]
Credit agreement termination date		May 14, 2019
Credit facility interest rate		4.15%
Mortgages
Debt Instrument [Line Items]
Maturity year	Nov. 01, 2023
Collateral value	$ 38,402	$ 39,283
Fixed interest rate	5.26%	5.26%
Other Notes and Contracts Payable
Debt Instrument [Line Items]
Other notes and contracts payable maturities in year	2024
Weighted-average interest rate	4.02%	4.49%

Other notes and contracts payable maturities in year.

No definition available.

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- Definition

Amount of assets pledged to secure a debt instrument.

+ References

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- Definition

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

+ References

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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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.

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- Definition

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

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- Definition

Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

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- Definition

The effective interest rate at the end of the reporting period.

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