Income Taxes - Accounting for Uncertainty in Income Taxes (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended																12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017		Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016		Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes (Textual) [Abstract]
Liability for unrecognized tax benefits	$ 1,891	$ 1,915								$ 1,891								$ 1,915	$ 1,891	$ 4,079	$ 3,417
Income tax related to accrued interest, net of federal benefit	400	500								400								500	400	300
Unrecognized tax benefits that would favorably impact the tax rate		1,900																1,900
Income tax benefit		6,705	[1]	$ 8,806		$ 8,722		$ 2,113		$ 6,814	[1]	$ 12,265		$ 6,448		$ 11,590		26,346	$ 37,117	$ 33,774
ASU 2016-09
Income Taxes (Textual) [Abstract]
Income tax benefit																		(3,000)
Internal Revenue Service (IRS)
Income Taxes (Textual) [Abstract]
Additional Income tax payment on audit for 2010 through 2012 tax year	$ 8,000
Maximum
Income Taxes (Textual) [Abstract]
Unrecognized tax benefits decrease amount over next twelve months		$ 100																$ 100

[1] Fluctuations in our effective income tax rate between quarters generally relates to the accounting for discrete income tax items in any given quarter, and revisions of estimates for certain income tax components during the year. For 2017: Our effective income tax rates for the first, second, third, and fourth quarters were 9%, 43%, 38%, and 31%, respectively. The first quarter 2017 effective income tax rate reflects an approximately $5 million net benefit resulting from Comcast’s exercise of 1.4 million vested stock warrants in January 2017 (see Note 10) and the fourth quarter effective income tax rate includes a $2 million benefit from the remeasurement of U.S.-based net deferred tax liabilities as required under the U.S. Tax reform enacted in December 2017 (see Note 7). For 2016: Our effective income tax rates for the first, second, third, and fourth quarters were 35%, 37%, 41%, and 35%, respectively.