Leases - Future minimum lease payments (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
2020	$ 21,017
2021	20,416
2022	19,370
2023	18,071
2024	15,718
Thereafter	105,544
Total minimum lease payments	200,136
2020	243
2021	248
2022	253
2023	258
2024	263
Thereafter	4,343
Total minimum lease payments	5,608
Less amount representing interest	3,018
Present value of net minimum lease payments	2,590
Fleet Leases Renewed Beyond Initial Lease Term
Lessee, Lease, Description [Line Items]
2020	17,600
2021	18,000
2022	11,800
2023	8,500
2024	5,400
Thereafter	$ 2,700