Notes and Contracts Payable (Schedule of Notes and Contracts Payable) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Notes and contracts payable	$ 585,102	$ 587,337
Senior Notes \| 4.60% unsecured notes
Debt Instrument [Line Items]
Notes and contracts payable	299,934	299,926
Senior Notes \| 4.30% unsecured notes
Debt Instrument [Line Items]
Notes and contracts payable	249,320	249,240
Trust Deed Notes
Debt Instrument [Line Items]
Notes and contracts payable	30,308	34,420
Other Notes and Contracts Payable
Debt Instrument [Line Items]
Notes and contracts payable	$ 5,540	$ 3,751

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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 210.9-03.13,16)
-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

Name:	us-gaap_DebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant