Collaboration Agreements - Additional Information (Detail)	1 Months Ended		3 Months Ended		7 Months Ended	9 Months Ended		34 Months Ended
	Aug. 31, 2017 USD ($) employee $ / shares shares	Mar. 31, 2014 USD ($)	Sep. 30, 2018 USD ($) shares	Sep. 30, 2017 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration			$ 7,163,000	$ 10,101,000		$ 16,818,000	$ 28,682,000
Estimated deferred revenue recognized within one year			8,905,000			$ 8,905,000			$ 9,229,000
Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement period						1 year
Collaborative Arrangement | Celgene Corporation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration			1,600,000	(100,000)		$ 1,400,000	500,000
Deferred revenue recorded under collaboration agreement			4,800,000			4,800,000
Estimated deferred revenue recognized within one year			3,900,000			3,900,000
Maximum success-based milestone payments		$ 21,500,000
Collaborative Arrangement | Celgene Corporation | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum success-based milestone payments		27,300,000
Collaborative Arrangement | Celgene Corporation | Upfront Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement upfront payment		$ 5,800,000						$ 2,100,000
Collaborative Arrangement | Merck Sharp & Dohme Corp.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration			200,000	8,800,000		1,600,000	15,400,000
Proceeds from collaborators			100,000	$ 2,300,000		1,000,000	5,600,000
Deferred revenue recorded under collaboration agreement			0			0
Collaborative Arrangement | Merck Sharp & Dohme Corp. | Upfront Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration							8,500,000
Proceeds from collaborators					$ 3,900,000		$ 12,000,000
Collaborative Arrangement | Lam Research Corporation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration			5,300,000			13,400,000
Maximum amount of royalties payable (ratio)	3
Maximum number of employees | employee	10
Exercise price of warrants | $ / shares	$ 16.75
Issued warrants, value	$ 6,700,000
Proceeds from collaborators			7,000,000			18,400,000
Deferred revenue recorded under collaboration agreement			2,000,000			2,000,000
Estimated deferred revenue recognized within one year			1,200,000			1,200,000
Customer deposits			9,600,000			9,600,000
nstg_ReimbursementOfCounterpartyCosts			100,000			200,000
Amounts due for services provided			0			$ 0
Payments for services provided			$ 0
Number of warrants exercised | shares			0
Collaborative Arrangement | Lam Research Corporation | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration	$ 50,000,000
Number of warrants, outstanding | shares	1,000,000