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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Income Tax [Line Items]
State income tax provision	$ 900,000	$ 1,300,000	$ 1,100,000
Charitable contribution carryforwards	18,303,000	$ 8,530,000
Federal R&D credit carryforwards	40,400,000
Increase in valuation allowance of deferred tax assets	$ 99,700,000
Tax rate	21.00%	21.00%	35.00%
Deferred tax asset , Switzerland tax reform	$ 57,000,000.0
Unrecognized tax reserves recorded during period	1,908,000	$ 3,104,000	$ 361,000
Interest and/or penalties accrued	0	0
Tax cuts and jobs act provisional adjustment			1,100,000
Interest and/or penalties	0	$ 0	$ 0
Federal
Income Tax [Line Items]
Operating loss carryforwards	426,100,000
Federal \| Expiring in 2025
Income Tax [Line Items]
Operating loss carryforwards	6,900,000
Federal \| Expiring in 2021
Income Tax [Line Items]
Charitable contribution carryforwards				$ 75,800
State
Income Tax [Line Items]
Operating loss carryforwards	$ 363,200,000
Remaining net operating loss carryforward, expiration year	2026
Research and development credit carryforwards with no expiration date	$ 13,500,000
State \| Expiring in 2024
Income Tax [Line Items]
Net operating loss carryforwards with no expiration date	1,500,000
State \| Expiring in 2025 \| Maximum
Income Tax [Line Items]
Operating loss carryforwards	100,000
State \| Expiring in 2021
Income Tax [Line Items]
Charitable contribution carryforwards				$ 75,800
Foreign
Income Tax [Line Items]
Operating loss carryforwards	$ 1,004,200,000
Remaining net operating loss carryforward, expiration year	2026
Net operating loss carryforwards with no expiration date	$ 3,400,000
Foreign \| Operating Loss Carryforwards Expiring 2022
Income Tax [Line Items]
Operating loss carryforwards	1,000,900,000
Expire in 2020
Income Tax [Line Items]
Federal R&D credit carryforwards	$ 200,000