Income Taxes - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Tax Credit Carryforward [Line Items]
Transfer of tax benefit to unrelated business	$ 3,100,000
Net proceeds from transfer of tax benefit to unrelated business	$ 2,900,000
Income tax expense recorded in prepaid asset			$ 2,800,000
Deferred tax liability related to investments		$ 0
Federal tax authority
Tax Credit Carryforward [Line Items]
Net operating loss carry-forwards		104,100,000
State tax authority
Tax Credit Carryforward [Line Items]
Net operating loss carry-forwards		122,500,000
Non-qualified stock options | Federal tax authority
Tax Credit Carryforward [Line Items]
Net operating loss carry-forwards		8,900,000
Non-qualified stock options | State tax authority
Tax Credit Carryforward [Line Items]
Net operating loss carry-forwards		2,300,000
Income Tax Expense
Tax Credit Carryforward [Line Items]
Amortization of prepaid expense		$ 193,000	$ 139,000