Income Taxes (Details Textual) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Jan. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017
Income Taxes [Line Items]
Income tax (expense) benefit		$ (8,806)		$ (12,265)	$ (19,641)	$ (30,303)
Effective income tax rate		38.00%		41.00%	30.00%	38.00%
Warrant Exercise
Income Taxes [Line Items]
Income tax (expense) benefit			$ 5,000
Scenario, Forecast
Income Taxes [Line Items]
Effective income tax rate							33.00%
ASU 2016-09
Income Taxes [Line Items]
Income tax (expense) benefit		$ 1,000			$ 2,000
ASU 2016-09 | Scenario, Forecast
Income Taxes [Line Items]
Income tax (expense) benefit							$ 2,000
Comcast Corporation
Income Taxes [Line Items]
Stock warrants exercised	1.4