Sirius XM Holdings Inc. Quarterly report pursuant to Section 13 or 15(d)

Cash, Cash Equivalents and Investments - Summary of available-for-sale securities' fair value and gross unrealized losses (Details)

Cash, Cash Equivalents and Investments - Summary of available-for-sale securities' fair value and gross unrealized losses (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value	$ 121,213	$ 197,939
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss	(144)	(431)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	12,732	12,148
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss	(16)	(22)
Available-for-sale securities, continuous unrealized loss position, fair value	133,945	210,087
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss	(160)	(453)
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value	117,964	192,699
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss	(143)	(422)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	10,737	12,148
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss	(11)	(22)
Available-for-sale securities, continuous unrealized loss position, fair value	128,701	204,847
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss	(154)	(444)
U.S. government and government agency debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value	3,249	5,240
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss	(1)	(9)
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	1,995	0
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss	(5)	0
Available-for-sale securities, continuous unrealized loss position, fair value	5,244	5,240
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss	$ (6)	$ (9)