Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 781,701	$ 482,738	$ 421,260	$ 402,040	$ 767,945	$ 511,521	$ 455,178	$ 372,489	$ 2,087,739	$ 2,107,133	$ 1,916,278
Gross profit	116,297	71,764	(82,680)	60,655	125,865	83,244	75,077	60,829	166,036	345,015	312,864
Operating income (loss)	36,005	9,543	(138,950)	3,506	43,462	17,580	13,825	6,681	(89,896)	81,548	62,138
Net income (loss) from continuing operations	$ 2,464	$ 11,625	$ (100,832)	$ 7,322	$ 60,484	$ 13,429	$ 11,616	$ (130,575)	$ (79,421)	$ (45,046)	$ 31,953
Basic EPS from continuing operations (in dollars per share)	$ 0.08	$ 0.38	$ (3.28)	$ 0.23	$ 1.88	$ 0.42	$ 0.36	$ (4.07)	$ (2.59)	$ (1.40)	$ 1.00
Diluted EPS from continuing operations (in dollars per share)	$ 0.08	$ 0.38	$ (3.28)	$ 0.23	$ 1.83	$ 0.41	$ 0.36	$ (4.07)	$ (2.59)	$ (1.40)	$ 0.99
Production Related Impairments or Charges [Abstract]
Inventory impairments and abandonments	$ 0	$ 0	$ 147,611	$ 1,007	$ 6,331	$ 168	$ 0	$ 0	$ 148,618	$ 6,499	$ 2,445
Gain (Loss) on Extinguishment of Debt [Abstract]
Loss on extinguishment of debt, net	$ (25,494)	$ 358	$ 216	$ 0	$ (1,935)	$ 0	$ 0	$ (25,904)	$ (24,920)	$ (27,839)	$ (12,630)