Income Taxes (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2015
U.S. statutory tax rate (as a percent)	24.50%			35.00%
Discrete tax benefit	$ (4,300,000)
Provisional transition tax	$ 0
Effective tax rate (as a percent)	(5.60%)				391.10%
Unrecognized tax benefits, exclusive of interest and penalties	$ 6,300,000			$ 6,300,000	$ 6,500,000
Unrecognized tax benefits from permanent tax adjustments that, if recognized, would affect the effective rate	3,500,000			3,500,000
Estimated unrecognized tax benefits resulting from possible resolution of reviews by domestic and international taxing authorities	3,000,000			3,000,000
Deferred tax asset valuation allowance	$ 59,500,000			$ 59,500,000		$ 35,800,000
Forecast
U.S. statutory tax rate (as a percent)		21.00%	24.50%