Basis of Presentation and Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) lease vessel	Sep. 30, 2019	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Restricted cash	$ 2,500,000		$ 2,500,000	$ 2,500,000
Restricted cash	$ 1,000,000		1,000,000
Number of vessels chartered to customers | vessel	6
Lease payments	$ 1,611,000
Time charter, term to completion	70 days	15 years
Number of noncancelable office leases | lease	2
Bulk Nordic Odin, Bulk Nordic Olympic, Bulk Nordic Odyssey, Bulk Nordic Orion and Bulk Nordic Oshima Loan Agreement
Property, Plant and Equipment [Line Items]
Restricted cash	$ 2,500,000		$ 2,500,000
Restricted cash	$ 1,000,000
Minimum
Property, Plant and Equipment [Line Items]
Vessel lease term	1 day
Maximum
Property, Plant and Equipment [Line Items]
Vessel lease term	72 days