Leases - Lease term and discount rates information (Details)	Dec. 31, 2020	Dec. 31, 2019
Leases
Operating leases (in years)	5 years 10 months 28 days	3 years 11 months 23 days
Finance leases (in years)	4 years 8 months 19 days	5 years 2 months 1 day
Operating leases (as a percent)	5.16%	5.29%
Finance leases (as a percent)	4.03%	4.01%