Variable Interest Entity - Financial Position of Variable Interest Entity (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 3,420,272	$ 3,374,194	$ 2,999,559	$ 2,492,516
Inventories	11,849,201	11,060,254
Property and equipment, net	1,455,008	1,770,516
Goodwill	6,705,130	6,705,507
Other long-term assets	800,446	269,067
TOTAL ASSETS	40,789,703	39,171,980
Long-term debt	4,140,351	4,172,892
Deferred income taxes	1,806,260	1,860,195
Other long-term liabilities	494,761	98,812
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	25,383	9,431
Accounts receivables, net	125,702	154,491
Inventories	138,477	185,602
Prepaid expenses and other	53,170	64,119
Property and equipment, net	23,806	30,961
Goodwill	82,309	82,309
Other intangible assets	74,598	74,429
Other long-term assets	53,004	9,169
TOTAL ASSETS	576,449	610,511
Accounts payable	119,012	165,053
Accrued expenses and other	34,043	49,191
Short-term debt	116,829	106,439
Long-term debt	47,119	60,973
Deferred income taxes	39,360	42,371
Other long-term liabilities	40,494	5,303
Total liabilities	$ 396,857	$ 429,330