Defined Contribution Plan (Details)	12 Months Ended
Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Minimum age of employee to cover under the plan	21 years
Employer matches vesting period	6 years
Percentage of employee contribution vested on their contribution	100.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employee compensation deferred percentage	90.00%

Percentage of employee contributions may be deferred to a defined contribution plan.

No definition available.

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Namespace Prefix:	nrbo_
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Period Type:	duration

- Definition

Employee eligibility age criteria under defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Period which the employer contribution will be vested under defined contribution plan, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	nrbo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of employee contribution vested on contribution made by employee.

+ References

No definition available.

+ Details

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Namespace Prefix:	nrbo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type: