Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Provision for income taxes	$ (6,123)		$ (5,659)	$ (19,491)	$ (8,023)
Effective tax rate	29.00%		24.50%	57.10%	20.80%
Effective income tax rate, Increase (decrease)				4.50%
Effective income tax rate, Tax Cuts and Jobs Act of 2018, increase (decrease)				36.30%
Tax Cuts And Jobs Act of 2017, incomplete accounting, change in tax rate, deferred tax asset, provisional income tax expense	$ 100	$ 37,700
Tax Cuts and Jobs Act of 2017, incomplete accounting, change in tax rate, partial reversal deferred tax liability, provisional income tax expense		37,700
Tax Cuts And Jobs Act Of 2017, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense		$ 9,100