Fair Value Measurements (Financial Assets and Liabilities Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Carrying Amount
Assets
Cash Equivalents	$ 256,370	$ 226,476
Liabilities
Mortgages payable (excluding deferred debt issuance costs, net)	1,056,147	1,059,587
Fair Value \| Level 1
Assets
Cash Equivalents	256,370	226,476
Fair Value \| Level 2
Liabilities
Mortgages payable (excluding deferred debt issuance costs, net)	$ 1,045,000	$ 1,054,000

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant