Basis of Presentation and Summary of Significant Accounting Policies - Lease (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2019 item	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jan. 01, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Right-of-use assets		$ 3,568,000		$ 3,568,000
Operating lease liability		$ 4,539,000		$ 4,539,000
Number of non-cancelable operating lease | item	2
Operating lease discount rate		7.00%		7.00%
Lease extension				true
Operating lease expense		$ 233,000	$ 48,000	$ 456,000	$ 142,000
Cash paid for amount included in lease liabilities		500,000		1,000,000
Sublease income		$ 86,000		$ 200,000
Noncancelable operating leases term		3 years 9 months 29 days		3 years 9 months 29 days
ASU 2016-02
Lessee, Lease, Description [Line Items]
Lease, practical expedients, package				true
Adjustment | ASU 2016-02
Lessee, Lease, Description [Line Items]
Right-of-use assets						$ 900,000
Operating lease liability						$ 2,000,000
Minimum
Lessee, Lease, Description [Line Items]
Operating lease term		2 years		2 years
Operating lease renewal term		5 years		5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease term		7 years		7 years
Operating lease renewal term		9 years		9 years