Balance Sheet Details (Narrative) (Details) (USD $)	12 Months Ended
Jul. 31, 2014	Jul. 31, 2013
Balance Sheet Details [Abstract]
Inventory reserve	$ 128,000us-gaap_InventoryWriteDown	$ 347,000us-gaap_InventoryWriteDown
Sale of silver	20,000us-gaap_ProceedsFromSaleOfOtherAssets1
Sale of silver held in inventory	58,000
Book value of silver sold	40,000pure_BookValueOfSilverSold
Gain on sale of silver	$ 20,000pure_GainOnSaleOfSilver	$ 18,000pure_GainOnSaleOfSilver

Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28360613&loc=d3e4542-108314

Name:	us-gaap_InventoryWriteDown
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration