Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Estimates annual effective tax rate	2.30%
Deferred tax benefit	$ 2,549,000	$ 2,572,000
Effective tax rate	1.80%	4.40%
Unrecognized tax benefits that would affect effective tax rate	$ 0
GILTI deferred amounts				$ 0
GILTI income tax	0		$ 0
Foreign Tax Authority | TransEnterix Italia
Income Tax Contingency [Line Items]
Net deferred tax asset	0
Valuation allowance	$ 0