Related Party Transactions - Management Agreement (Details) - SP General Services LLC - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Management fee percentage, quarterly basis (as a percent)					1.50%
Management agreement renewal, term (in years)					1 year
Notice period prior to management agreement renewal, period (in days)					60 days
Management Fee
Related Party Transaction [Line Items]
Waived management fee				$ 2,186
Related Party Transaction, Management Fee, Reduction As A Percentage	25.00%
Services fees and reimbursable expenses		$ 1,461	$ 1,945		$ 2,642	$ 5,854
Unpaid amount for management fee		870			870		$ 27
Reimbursable Expenses
Related Party Transaction [Line Items]
Services fees and reimbursable expenses		509	$ 1,539		1,661	$ 5,108
Deferred fees payable to related party		$ 796			$ 796		$ 409