Related Parties - Additional Information (Detail) - USD ($)	3 Months Ended				9 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Cirius Therapeutics, Inc., [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services				$ 44,000	$ 281,000	$ 94,000
Revenue recognized from related parties agreement			$ 26,000		120,000
Viscient Biosciences [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services				$ 0		$ 0
Viscient Biosciences [Member] | Study Materials [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services					2,000
Revenue recognized from related parties agreement			0		2,000
Viscient Biosciences [Member] | Research Services [Member] | Scenario, Forecast [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services	$ 142,000
Viscient Biosciences [Member] | Samsara [Member] | Primary Human Cell-based Products [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services					91,000
Revenue recognized from related parties agreement			$ 88,000		$ 91,000
Viscient Biosciences [Member] | Samsara [Member] | Primary Human Cell-based Products [Member] | Scenario, Forecast [Member]
Related Party Transaction [Line Items]
Amount of transactions with related party for providing services	$ 55,000	$ 55,000