Lease Obligations - Summary of the lease terms and discount rates (Details)	Jun. 30, 2021	Dec. 31, 2020
Leases [Abstract]
Weighted-average remaining lease term - finance leases	1 month 6 days	4 months 24 days
Weighted-average remaining lease term - operating leases	3 years 2 months 12 days	3 years 4 months 24 days
Weighted-average discount rate - finance leases	3.10%	2.60%
Weighted-average discount rate - operating leases	3.90%	3.90%