Note 4 - Property and Equipment, Net (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Depreciation, Depletion and Amortization	$ 57,000	$ 30,000	$ 27,000
Property, Plant and Equipment, Disposals			200,000
Fixed Asset, Net Book Value, Disposal			0
Gain (Loss) on Disposition of Property Plant Equipment			$ 100,000

Net book value for property disposed of during the current period.

No definition available.

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Namespace Prefix:	prto_
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Balance Type:	debit
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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

+ References

+ Details

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- Definition

Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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