Collaboration Agreements - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		7 Months Ended	9 Months Ended		12 Months Ended	26 Months Ended	34 Months Ended
	Feb. 28, 2018 USD ($)	Aug. 31, 2017 USD ($) employee $ / shares shares	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue			$ 30,604	$ 28,616		$ 88,637	$ 76,700
Estimated deferred revenue recognized within one year			4,389			4,389			$ 4,389		$ 9,890
Collaborative Arrangement | Celgene Corporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue				1,600		4,400	1,400
Proceeds from collaborators			800			$ 1,100
Collaborative agreement period						1 year
Maximum success-based milestone payments	$ 19,000
Collaborative Arrangement | Celgene Corporation | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum success-based milestone payments	24,800
Collaborative Arrangement | Celgene Corporation | Upfront Payment Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration agreement upfront payment	$ 5,800									$ 2,100
Collaborative Arrangement | Merck Sharp & Dohme Corp.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue				200			1,600
Collaborative Arrangement | Merck Sharp & Dohme Corp. | Upfront Payment Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue								$ 8,500
Proceeds from collaborators					$ 3,900			$ 12,000
Collaborative Arrangement | Lam Research Corporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum amount of royalties payable (ratio)		3
Maximum number of employees | employee		10
Exercise price of warrants | $ / shares		$ 16.75
Issued warrants, value		$ 6,700
Revenue			4,000	5,300		$ 13,200	13,400
Proceeds from collaborators			3,400	7,000		11,700	18,400		46,800
Deferred revenue recorded under collaboration agreement			500			500			500
Estimated deferred revenue recognized within one year			500			500			500
Customer deposits			5,300			5,300			$ 5,300
nstg_ReimbursementOfCounterpartyCosts			$ 200	$ 100		$ 600	$ 200
Number of warrants exercised | shares						0
Collaborative Arrangement | Lam Research Corporation | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of warrants, outstanding | shares		1,000,000
Revenue		$ 50,000