Notes and Contracts Payable (Schedule of Notes and Contracts Payable) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Weighted-average interest rate	4.51%	4.52%
Senior Notes | 4.60% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes maturity date	Nov. 15, 2024
Debt instrument unamortized discount amount	$ 66	$ 74
Effective interest rate	4.60%
Senior Notes | 4.30% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes maturity date	Feb. 01, 2023
Debt instrument unamortized discount amount	$ 680	760
Effective interest rate	4.35%
Trust Deed Notes
Debt Instrument [Line Items]
Maturity year	2023
Debt collateralized by land and buildings	$ 50,514	$ 52,414
Weighted-average interest rate	5.34%	5.39%
Other Notes and Contracts Payable
Debt Instrument [Line Items]
Weighted-average interest rate	4.21%	5.30%
Other notes and contracts payable maturities in year	2032