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Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Leasehold Improvements |  |
Property Plant And Equipment [Line Items] |  |
Lessor-paid tenant improvements | $ 6.6 | $ 1.3
Construction in Progress |  |
Property Plant And Equipment [Line Items] |  |
Lessor-paid tenant improvements |  | $ 5.0
Laboratory Equipment |  |
Property Plant And Equipment [Line Items] |  |
Minimum percentage of fair value on present value of expected payments | 90.00% | 90.00%
Assets under capital lease | $ 1.3 | $ 1.4
Accumulated depreciation of capital lease | $ 0.9 | $ 0.2

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- Definition The total gross amount less the charge for the use of the long-lived depreciable assets subject to a lease meeting the criteria for capitalization. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
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- Definition This item represents the deferred credit for an incentive or inducement received by a lessee from a lessor, in order to motivate the lessee to enter the lease agreement, which incentive or inducement is to be recognized as a reduction of rental expense over the lease term. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 55 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=77891322&loc=d3e41620-112719 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e40010-112707 + Details
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