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Operating Leases - Narrative (Detail) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) ft² location	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Area of operating lease | ft²	37,829
Number of office space locations | location	1
Operating lease, right-of-use asset	$ 2.7
Operating lease, liability	$ 3.3
Operating lease expense excluding rent		$ 0.4
Accounting Standards Update 2016-02
Operating lease, right-of-use asset			$ 2.9
Operating lease, liability			$ 3.6

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- Definition

Lessee Leasing Agreements, Operating Leases, Area under Lease

+ References

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- Definition

Lessee Leasing Agreements, Operating Leases, locations

+ References

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- Definition

Operating Lease Expense Excluding Rent

+ References

No definition available.

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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