Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components Of Income Taxes [Line Items]
Deferred tax assets	$ 0	$ 856,000
Valuation allowance for deferred tax assets	168,211,000	145,753,000
Net operating loss carryforwards	298,400,000
Reserve for uncertain tax positions	7,388,000	7,777,000	$ 7,660,000
Unrecognized tax benefits available to offset uncertain tax position liabilities	6,748,000	7,360,000
Net unrecognized benefits	640,000	417,000
Federal | Canada
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	191,300,000
Capital loss carryforwards	289,500,000
Federal | Canada | Research and Development
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	13,500,000
Scientific, research and experimental development pool	11,400,000
Foreign | U.S.
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	66,200,000
Operating loss carryforwards subject to expiration	59,200,000
Current income tax expense recorded as result of change in federal tax rate		21,500,000
Incremental U.S. tax for unremitted earnings in foreign subsidiaries		0
Tax liability recorded for unremitted earnings in foreign subsidiaries		$ 0
Foreign | Switzerland
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	30,800,000
Foreign | UK
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	10,100,000
State and Local | U.S.
Components Of Income Taxes [Line Items]
Net operating loss carryforwards	$ 43,900,000