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Real Estate and Intangible Assets - Carrying Value of Intangible Assets and Accumulated Amortization (Detail) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Finite-Lived Intangible Assets [Line Items] |  |
Below market leases and deferred revenue, gross | $ (34,098) | $ (29,807)
Below market leases and deferred revenue, accumulated amortization | 14,344 | 12,502
Lease Intangibles |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 216,404 | 204,020
Accumulated Amortization | (106,207) | (92,572)
In-place leases |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 88,762 | 83,894
Accumulated Amortization | (46,418) | (40,445)
Leasing costs |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 64,986 | 59,671
Accumulated Amortization | (32,252) | (28,092)
Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 62,656 | 60,455
Accumulated Amortization | (27,537) | (24,035)
Above market leases and below market leases and deferred revenue |  |
Finite-Lived Intangible Assets [Line Items] |  |
Finite-lived intangible assets (liabilities), gross | (17,681) | (15,256)
Finite-lived intangible assets (liabilities), accumulated amortization | 4,621 | 3,521
Above market leases |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 16,417 | 14,551
Accumulated Amortization | $ (9,723) | $ (8,981)

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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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