Income Taxes (Details) - USD ($)	3 Months Ended				9 Months Ended	12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
U.S. statutory tax rate (as a percent)					24.50%				35.00%
Provisional discrete tax benefit		$ (3,000,000)	$ (4,300,000)
Provisional transition tax					$ 0
Income tax provision (benefit)					500,000
Offsetting benefit to continuing operations					$ (500,000)
Effective tax rate (as a percent)	120.80%			(737.00%)	(37.50%)					132.30%
Unrecognized tax benefits, exclusive of interest and penalties	$ 5,600,000				$ 5,600,000					$ 6,500,000
Unrecognized tax benefits from permanent tax adjustments that, if recognized, would affect the effective rate	2,800,000				2,800,000
Estimated unrecognized tax benefits resulting from possible resolution of reviews by domestic and international taxing authorities	2,800,000				2,800,000
Deferred tax asset valuation allowance	$ 72,700,000				$ 72,700,000
Forecast
U.S. statutory tax rate (as a percent)						21.00%	21.00%	24.50%