ASU 842 - Leases - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 24,132		$ 0
Operating lease liabilities	$ 30,065
Operating leases, weighted average remaining lease term (in years)	6 years 7 months 13 days
Operating leases, weighted average discount rate (percent)	6.83%
Minimum
Lessee, Lease, Description [Line Items]
Incremental borrowing rate used for lease obligations (percent)	4.08%	4.08%
Maximum
Lessee, Lease, Description [Line Items]
Incremental borrowing rate used for lease obligations (percent)	7.36%	7.36%
ASU No. 2016-02
Lessee, Lease, Description [Line Items]
Operating lease assets		$ 26,449
Operating lease liabilities		$ 32,932