Summary of Significant Accounting Policies - Cumulative Effect of the Changes Made to the Company's Balance Sheet upon Adopting ASC 842 (Details) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Operating lease ROU assets	$ 30,600	$ 35,486
Prepaid expenses	7,137	6,362	$ 6,781
Liabilities:
Accrued expenses	14,718	9,056	$ 9,778
Operating lease liability, current portion	4,805	4,455
Operating lease liability	$ 30,947	31,334
ASU 2016-02
ASSETS
Operating lease ROU assets		35,486
Prepaid expenses		(419)
Liabilities:
Accrued expenses		(722)
Operating lease liability, current portion		4,455
Operating lease liability		$ 31,334