Marketable Investment Securities, Restricted Cash and Cash Equivalents, and Other Investment Securities - Narrative (Details)	6 Months Ended
	Jun. 30, 2017	Feb. 28, 2017
Commercial paper | Maximum
Other investment securities:
Debt term of Maturity	365 days
Unsecured Debt Term Of Maturity	365 days
Corporate securities | Maximum
Other investment securities:
Debt term of Maturity	18 months
Unsecured Debt Term Of Maturity	18 months
NagraStar
Other investment securities:
Ownership interest (as a percent)		50.00%