Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Renewal term (up to)	10 years
Operating lease right-of-use asset	$ 8,700	$ 10,000
Operating lease liabilities	$ 10,850	$ 12,600
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherAccruedLiabilitiesCurrentAndNoncurrent	us-gaap:OtherAccruedLiabilitiesCurrentAndNoncurrent
Lease cost	$ 2,420	$ 2,451
Rent expense			$ 2,100
Minimum sublease rental income, due in 2021	100
Indemnifications related to contract underwriting services
Loss Contingencies [Line Items]
Amount paid for remedies (less than)	$ 100	$ 100