Revision of Previously Issued Financial Statements - Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 38,169,265	$ 36,709,046
Cost of goods sold	37,131,585	35,744,169
Gross profit	1,037,680	964,877
Operating expenses:
Distribution, selling, and administrative	520,547	525,077
Depreciation	55,854	50,866
Amortization	40,226	32,096
Warrants	0	467,375
Employee severance, litigation, and other	21,066	18,868
Pension settlement	0	48,731
Operating income (loss)	399,987	(178,136)
Other income	(123)	(310)
Interest expense, net	36,972	33,741
Income (loss) before income taxes	363,138	(211,567)
Income tax expense (benefit)	115,892	(541,206)
Net income	$ 247,246	$ 329,639
Earnings per share:
Basic (usd per share)	$ 1.13	$ 1.60
Diluted (usd per share)	$ 1.11	$ 1.45
Weighted average common shares outstanding:
Basic (shares)	218,661	206,180
Diluted (shares)	221,979	226,718
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue		$ 36,709,046
Cost of goods sold		35,744,169
Gross profit		964,877
Operating expenses:
Distribution, selling, and administrative		528,296
Depreciation		49,342
Amortization		32,096
Warrants		467,375
Employee severance, litigation, and other		18,868
Pension settlement		48,731
Operating income (loss)		(179,831)
Other income		(310)
Interest expense, net		30,879
Income (loss) before income taxes		(210,400)
Income tax expense (benefit)		(540,777)
Net income		$ 330,377
Earnings per share:
Basic (usd per share)		$ 1.60
Diluted (usd per share)		$ 1.46
Weighted average common shares outstanding:
Basic (shares)		206,180
Diluted (shares)		226,718
Adjustments [Member] | Error Correction, Lease Accounting [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue		$ 0
Cost of goods sold		0
Gross profit		0
Operating expenses:
Distribution, selling, and administrative		(3,219)
Depreciation		1,524
Amortization		0
Warrants		0
Employee severance, litigation, and other		0
Pension settlement		0
Operating income (loss)		1,695
Other income		0
Interest expense, net		2,862
Income (loss) before income taxes		(1,167)
Income tax expense (benefit)		(429)
Net income		$ (738)
Earnings per share:
Basic (usd per share)		$ 0.00
Diluted (usd per share)		$ (0.01)
Weighted average common shares outstanding:
Basic (shares)		0
Diluted (shares)		0