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Properties, net (Details) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
--- | --- | --- | --- | ---
Properties |  |  |  |
Gross | $ 4,158,616 | $ 4,014,336 | $ 3,811,950 | $ 3,859,960
Operating properties, net | 2,920,529 | 2,751,488 |  |
Operating properties, net [Member] |  |  |  |
Properties |  |  |  |
Less: accumulated depreciation | (700,363) | (703,083) |  |
Operating properties, net [Member] | Land [Member] |  |  |  |
Properties |  |  |  |
Gross | 463,305 | 439,355 |  |
Operating properties, net [Member] | Buildings and improvements [Member] |  |  |  |
Properties |  |  |  |
Gross | $ 3,157,587 | $ 3,015,216 |  |

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- Definition Amount, before accumulated depreciation, of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + 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 III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition The cumulative amount of depreciation for real estate property held for investment purposes. + 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 210.7-03.1(3)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + 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 Carrying amount of income producing properties held for rental. + 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 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Details
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- Details
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- Details
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