Leases - Maturities of lease liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Year 1	$ 39,017
Year 2	37,983
Year 3	33,112
Year 4	26,386
Year 5	17,607
Thereafter	139,172
Total lease payments	293,277
Less: Imputed interest	50,367
Total lease liabilities	242,910
Short-term lease liabilities	34,041
Long-term lease liabilities	208,869
Finance Leases
Year 1	738
Year 2	749
Year 3	759
Year 4	770
Year 5	781
Thereafter	12,862
Total lease payments	16,659
Less: Imputed interest	8,023
Total	8,636	$ 0
Short-term lease liabilities	157
Long-term lease liabilities	8,479
Operating Leases
Year 1	38,279
Year 2	37,234
Year 3	32,353
Year 4	25,616
Year 5	16,826
Thereafter	126,310
Total lease payments	276,618
Less: Imputed interest	42,344
Total	234,274
Short-term lease liabilities	33,884
Long-term lease liabilities	$ 200,390