Transactions with Affiliates - Other Transactions, Reimbursement of Common Overhead Expenses (Details) - PMT - USD ($)		3 Months Ended
	Sep. 12, 2016	Mar. 31, 2020	Mar. 31, 2019
Transactions with Affiliates
Expense reimbursement amount, per quarter, relating to personnel	$ 120,000
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company		$ 2,931,000	$ 1,926,000
Payments and settlements during the period		33,683,000	15,189,000
Common overhead incurred
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company		1,540,000	1,236,000
Compensation
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company		120,000	120,000
Expenses incurred by related party (reporting entity), net
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company		$ 1,271,000	$ 570,000