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Summary of Significant Accounting Policies (Details) |  | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Oct. 25, 2017 USD ($) | Jun. 30, 2018 USD ($) | Dec. 31, 2017 USD ($) segment | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Jan. 01, 2017 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Number of operating segments | segment |  |  | 1 |  |  |
Fixed asset impairment |  | $ 2,200,000 | $ 400,000 | $ 2,000,000 | $ 0 |
Furniture |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Estimated useful life of the asset |  |  | 5 years |  |  |
Computer equipment |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Estimated useful life of the asset |  |  | 3 years |  |  |
Retained Earnings | Accounting Standards Update 2016-09 |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  | $ 300,000
IVF Japan |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Fixed fee revenue per treatment cycle | $ 1,000 |  |  |  |  |
Reimbursed amount of lab operations and personnel costs | $ 200,000 |  | $ 55,000 |  |  |
Minimum |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Short-term investments, maturity term |  |  | 1 year |  |  |
Minimum | Laboratory equipment |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Estimated useful life of the asset |  |  | 3 years |  |  |
Maximum |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Short-term investments, maturity term |  |  | 2 years |  |  |
Maximum | Laboratory equipment |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Estimated useful life of the asset |  |  | 5 years |  |  |

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