Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016
Other Liabilities Disclosure [Abstract]
Accrued bonus and deferred compensation	$ 19,620		$ 36,753
Customer deposits	17,562		11,704
Accrued interest	16,318		11,024
Accrued warranty expense	14,583	$ 15,816	18,091	$ 25,386	$ 32,309	$ 39,131
Litigation accrual	2,886		3,899
Income tax liabilities	1,168		811
Other	25,800		25,377
Total other liabilities	$ 97,937		$ 107,659