Inventory - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventory transferred into property, plant and equipment for internal use	$ 2.5

Inventory transferred to property and equipment for internal use.

No definition available.

Name:	nstg_InventoryTransferredToPropertyAndEquipmentForInternalUse
Namespace Prefix:	nstg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration