Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 497.7	$ 1,170.3	$ 1,189.9	$ 298.1	$ 433.9	$ 994.6	$ 1,013.3	$ 221.5	$ 3,156.0	$ 2,663.4	$ 2,642.1
Cost of sales									2,130.5	1,778.3	1,669.5
Cost of sales—impairment, restructuring and other									5.9	20.5	0.0
Gross profit	89.5	423.4	472.1	34.5	73.7	347.6	409.2	34.0	1,019.6	864.6	972.6
Operating expenses:
Selling, general and administrative									601.3	540.1	550.9
Impairment, restructuring and other									7.4	132.3	4.9
Other (income) expense, net									1.3	(6.7)	(16.6)
Income (loss) from operations									409.6	198.9	433.4
Equity in (income) loss of unconsolidated affiliates									(3.3)	(4.9)	29.0
Interest expense									101.8	86.4	76.1
Other non-operating (income) expense, net									(270.5)	1.7	13.4
Income from continuing operations before income taxes									581.6	115.7	314.9
Income tax expense (benefit) from continuing operations									144.9	(11.9)	116.6
Income (loss) from continuing operations	(55.5)	178.0	396.9	(82.6)	(130.6)	125.5	152.7	(20.0)	436.7	127.6	198.3
Income (loss) from discontinued operations, net of tax	(2.6)	23.6	(0.5)	2.9	(16.3)	(42.7)	(3.7)	(1.2)	23.5	(63.9)	20.5
Net income (loss)	(58.1)	201.6	396.4	(79.7)	(146.9)	82.8	149.0	(21.2)	460.2	63.7	218.8
Net (income) loss attributable to noncontrolling interest									0.5	0.0	(0.5)
Net income (loss) attributable to controlling interest	$ (57.9)	$ 201.7	$ 396.5	$ (79.6)	$ (147.0)	$ 82.9	$ 148.9	$ (21.2)	$ 460.7	$ 63.7	$ 218.3
Basic income (loss) per common share:
Income from continuing operations (USD per share)	$ (0.99)	$ 3.21	$ 7.17	$ (1.49)	$ (2.36)	$ 2.27	$ 2.70	$ (0.35)	$ 7.88	$ 2.27	$ 3.33
Income (loss) from discontinued operations (USD per share)	(0.05)	0.42	(0.01)	0.05	(0.29)	(0.77)	(0.06)	(0.02)	0.42	(1.14)	0.35
Basic net income (loss) per common share (USD per share)	(1.04)	3.63	7.16	(1.44)	(2.65)	1.50	2.64	(0.37)	8.30	1.13	3.68
Diluted income (loss) per common share:
Income from continuing operations (USD per share)	(0.99)	3.15	7.10	(1.49)	(2.36)	2.23	2.66	(0.35)	7.77	2.23	3.29
Income (loss) from discontinued operations (USD per share)	(0.05)	0.41	(0.01)	0.05	(0.29)	(0.76)	(0.07)	(0.02)	0.41	(1.11)	0.34
Diluted net income (loss) per common share (USD per share)	$ (1.04)	$ 3.56	$ 7.09	$ (1.44)	$ (2.65)	$ 1.47	$ 2.59	$ (0.37)	$ 8.18	$ 1.12	$ 3.63