Investments in Affiliates Accounted for Using the Equity Method (Summary of Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Current assets	$ 443,480		$ 443,480			$ 246,587
Investments in affiliates	157,484		157,484			167,643
Other assets	192,993		192,993			295,693
Total assets	12,805,686		12,805,686			11,356,020
Long-term debt	2,599,521		2,599,521			2,604,371
Deferred income tax liabilities	1,964,300		1,964,300			1,578,643
Other liabilities	116,303		116,303			133,020
Equity	7,558,395	$ 5,874,276	7,558,395	$ 5,874,276	$ 6,528,484	6,506,069	$ 5,763,224	$ 4,488,017
Total liabilities and shareholders' equity	12,805,686		12,805,686			11,356,020
Operating expenses, net	(236,402)	(230,990)	(682,981)	(713,218)
Operating income (loss)	10,490	(3,946)	24,530	(50,872)
Share of earnings (loss) of affiliates, net	(9,035)	1,921	(7,504)	(2,443)
Realized and unrealized gains (losses) on financial instruments, net	1,417,560	170,617	1,484,968	2,019,222
Other income (expense), net	1,375,661	135,982	1,381,927	1,920,936
Income tax benefit (expense)	(379,188)	(31,396)	(387,817)	(511,101)
Net earnings (loss)	$ 1,006,989	100,668	$ 1,018,717	1,359,048
Liberty Broadband
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	23.70%		23.70%
Current assets	$ 402,492		$ 402,492			52,133
Investments in affiliates	12,450,425		12,450,425			12,194,674
Other assets	8,772		8,772			9,535
Total assets	12,861,689		12,861,689			12,256,342
Long-term debt	1,318,664		1,318,664			572,944
Deferred income tax liabilities	1,036,672		1,036,672			999,757
Other liabilities	19,103		19,103			15,695
Equity	10,487,250		10,487,250			10,667,946
Total liabilities and shareholders' equity	12,861,689		12,861,689			$ 12,256,342
Revenues	4,219	3,713	12,437	10,918
Operating expenses, net	(20,547)	(11,301)	(45,872)	(31,873)
Operating income (loss)	(16,328)	(7,588)	(33,435)	(20,955)
Share of earnings (loss) of affiliates, net	188,586	61,633	408,396	141,882
Gain (loss) on dilution of investment in affiliate	(35,284)	(11,219)	(140,610)	(68,944)
Realized and unrealized gains (losses) on financial instruments, net	(39,324)	(433)	(39,324)	(433)
Other income (expense), net	(3,711)	(5,773)	(14,512)	(17,829)
Income tax benefit (expense)	(24,979)	(9,124)	(47,183)	(8,474)
Net earnings (loss)	$ 68,960	$ 27,496	$ 133,332	$ 25,247