Income Taxes - Newsday and Chicago Cubs Transactions (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 22, 2019	Mar. 31, 2019	Mar. 31, 2018	Aug. 21, 2018	Oct. 27, 2009
Income Tax Contingency [Line Items]
Proceeds from the sales of investments		$ 107,500	$ 3,890
Gain on investment transaction		86,272	$ 3,888
CEV LLC
Income Tax Contingency [Line Items]
Ownership percentage in common stock by third party					95.00%
Ownership percentage in common stock	5.00%			5.00%
Proceeds from the sales of investments	$ 107,500
Gain on investment transaction		86,000
Gain (loss) on Investments, after tax		66,000
Deferred tax liability		69,000
CEV LLC | Tax Year 2009
Income Tax Contingency [Line Items]
IRS proposed tax		182,000
IRS proposed gross valuation misstatement penalty		73,000
After-tax interest on proposed tax and penalty		86,000
Estimated federal income taxes before interest and penalties		225,000
Deferred tax liability		69,000
Income taxes paid		$ 167,000