Leases - Time Charter-In Contracts Narrative (Details) $ in Thousands										3 Months Ended	9 Months Ended
	Sep. 06, 2021 route $ / d	Jul. 08, 2021 $ / d	Jun. 28, 2021 $ / d	May 04, 2021 $ / d	Dec. 22, 2020 route t $ / d	Dec. 25, 2019 $ / d	Dec. 09, 2018 t $ / d	May 04, 2018 t $ / d	Apr. 28, 2017 t $ / d	Mar. 31, 2022 USD ($) t	Sep. 30, 2021 USD ($)	Mar. 17, 2022	Dec. 31, 2021 USD ($)	Jul. 07, 2021	Jul. 01, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Dead weight tonnage of operating fleet | t										3,190,000
Fair value below contract value of time charters acquired																		$ 1,800
Increase to lease modification liability																$ 1,000	$ 4,500
Increase to lease modification right-of-use asset																$ 1,000	$ 4,500
Total lease liabilities										$ 18,648
Operating lease right-of-use assets										18,654			$ 17,017
Chartered-in contracts greater than 12 months
Lessee, Lease, Description [Line Items]
Total lease liabilities										16,378
Operating lease right-of-use assets										16,377			$ 15,039
2013 Built Japanese Vessel
Lessee, Lease, Description [Line Items]
Dead weight tonnage of operating fleet | t									61,400
Charters agreement term									4 years
Charters agreement term, extension option									2 years
Increase to lease liability and the corresponding right-of-use asset											$ 5,000
Discount rate		1.36%
2013 Built Japanese Vessel | First Four Years
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d									12,800
2013 Built Japanese Vessel | First Optional Year
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d		13,800							13,800
2013 Built Japanese Vessel | Second Optional Year
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d									14,300
2013 Built Ultramax Vessel
Lessee, Lease, Description [Line Items]
Dead weight tonnage of operating fleet | t								61,425
Charters agreement term								3 years
Charters agreement term, extension option								2 years
Increase to lease liability and the corresponding right-of-use asset											5,800
2013 Built Ultramax Vessel | First Optional Year
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d								13,750
2013 Built Ultramax Vessel | Second Optional Year
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d			13,750					14,750
Discount rate			1.34%
2013 Built Ultramax Vessel | First Three Years
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d								12,700
2016 Built Ultramax Vessel
Lessee, Lease, Description [Line Items]
Dead weight tonnage of operating fleet | t							62,487
Charters agreement term							2 years
2016 Built Ultramax Vessel | First Two Years
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d						11,600	14,250
2016 Built Ultramax Vessel | Third Year Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d							15,250
2016 Built Ultramax Vessel | Additional Year Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d				12,600
Increase to lease liability and the corresponding right-of-use asset										6,900	$ 4,300
Discount rate				1.38%								4.48%
2021 Built Ultramax Vessel
Lessee, Lease, Description [Line Items]
Dead weight tonnage of operating fleet | t					63,634
Charters agreement term					12 months
Charters agreement term, extension option					3 months
Discount rate														1.33%
Charter agreement term, initial period					15 months
Total lease liabilities															$ 9,100
Operating lease right-of-use assets															$ 9,100
2021 Built Ultramax Vessel | Additional Year Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d	10,750
Total lease liabilities										0
Operating lease right-of-use assets										$ 0
2021 Built Ultramax Vessel | Twelve Month Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d					5,900
Vessel hire rate (usd per day)					57.00%
Number of routes | route					10
2021 Built Ultramax Vessel | Three Month Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d					6,500
Shared scrubber benefit					50.00%
2021 Built Ultramax Vessel | Twelve To Fifteen Month Option
Lessee, Lease, Description [Line Items]
Vessel hiring rate (in dollars per day) | $ / d	11,250
Vessel hire rate (usd per day)	57.50%
Number of routes | route	10
Minimum
Lessee, Lease, Description [Line Items]
Charters agreement term	12 months
Charters agreement term, extension option					11 months
Minimum | 2021 Built Ultramax Vessel
Lessee, Lease, Description [Line Items]
Charters agreement term	12 months
Maximum
Lessee, Lease, Description [Line Items]
Charters agreement term	15 months
Charters agreement term, extension option					13 months
Maximum | 2021 Built Ultramax Vessel
Lessee, Lease, Description [Line Items]
Charters agreement term	15 months