Nature of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands			1 Months Ended									2 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Dec. 20, 2016 USD ($) $ / shares shares	Aug. 21, 2015	Nov. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	May 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jan. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jan. 31, 2017 USD ($) $ / shares shares	May 31, 2014 USD ($)	Sep. 30, 2011 USD ($)	Aug. 31, 2013 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2018 USD ($) Segment Patient Site	Sep. 30, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 31, 2017 $ / shares
Nature Of Operations [Line Items]
Number of reportable segments | Segment															1
Number of patients to enroll under double-blinded study plan with uncontrolled type 2 diabetes and obesity | Patient															500
Number of sites consider for trial of EndoBarrier Therapy | Site															25
Percentage of reducing headcount		46.00%
Non-recurring charges														$ 1,100
Issuance of shares, value						$ 1,600	$ 1,600			$ 30,800	$ 72,500	$ 52,500
Repayment of convertible term promissory notes											$ 6,000					$ 214
Common stock issued, price per share | (per share)									$ 0.83										$ 0.022
Private placement amount received	$ 1,000
Proceeds from issuance of common stock									$ 200						$ 3,607	198
Accumulated deficit				$ (264,745)											(264,745)			$ (259,121)
Working capital deficit				(3,900)											(3,900)
Cash used in operating activities															(5,202)	$ (7,647)
Cash and cash equivalents				3,104											$ 3,104			$ 3,034
Tranche One
Nature Of Operations [Line Items]
Private placement amount received				2,200
Private Placement
Nature Of Operations [Line Items]
Issuance of shares, value				$ 5,000
Scenario, Forecast | Tranche Two
Nature Of Operations [Line Items]
Private placement amount received			$ 2,800
Scenario, Forecast | Private Placement
Nature Of Operations [Line Items]
Private placement amount received																	$ 6,610
2017 Senior Secured Convertible Promissory Note
Nature Of Operations [Line Items]
Debt principal amount								$ 5,000
Interest rate during period								5.00%
Maturity Date								Dec. 31, 2018
2018 Senior Secured Convertible Promissory Note and Warrant
Nature Of Operations [Line Items]
Debt principal amount					$ 1,750
Interest rate during period					10.00%
Maturity Date					May 30, 2023
Common stock
Nature Of Operations [Line Items]
Stock issued, shares | shares	1,397,300								249,632
CHESS Depositary Interests
Nature Of Operations [Line Items]
Stock issued, shares | shares	69,865,000								12,481,600
Common stock issued, price per share | $ / shares	$ 0.22
Restructuring Charges
Nature Of Operations [Line Items]
Non-recurring charges													$ 400
Employee Severance
Nature Of Operations [Line Items]
Non-recurring charges														600
Facility Closing
Nature Of Operations [Line Items]
Non-recurring charges														$ 100