Income Taxes - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Income Taxes [Line Items]
Valuation allowance, additional	$ 28,100
Net operating loss associated with excess benefits related to stock compensation	9,600
Accrued interest or penalties related to uncertain tax positions	2
Total amount of unrecognized tax benefits	97
Canada | Research and development
Income Taxes [Line Items]
Tax credit carryforwards	$ 1,500
Tax credit carryforward expiration year	2036
Domestic tax authority
Income Taxes [Line Items]
Net operating loss carryforwards	$ 52,100
Net operating losses expiration beginning period	2026
Federal net operating losses expiration ending Period	2036
Tax credit carryforwards	$ 9,900
Federal credit carryforward expiration, beginning period	2017
Federal credit carryforward expiration ending Period	2036
State and local jurisdiction
Income Taxes [Line Items]
Net operating loss carryforwards	$ 52,500
Net operating losses expiration beginning period	2028
Tax credit carryforwards	$ 1,700
Foreign tax authority | Ireland
Income Taxes [Line Items]
Net operating loss carryforwards	$ 2,900