Assets And Liabilities Measured At Fair Value Realized Unrealized Gain Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	$ 369	$ 606	$ 1,186	$ 942
Fair Value Option Securities - AFS
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gain (losses) AFS	130	260	552	608
Fair Value Option Securities - Liberty Broadband
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	365	490	906	651
Exchangeable Senior Debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	(91)	(138)	(230)	(313)
Other Financial Instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	$ (35)	$ (6)	$ (42)	$ (4)