Marketable Investment Securities, Restricted Cash and Cash Equivalents, and Other Investment Securities - Unrealized Gain (Losses) On Marketable Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Components of our available-for-sale investments
Debt securities	$ 557,911	$ 2,131,745
Total marketable investment securities	640,191	2,208,715
Unrealized Gains (Losses) on Marketable Investment Securities
Unrealized Gains	98,196	181,189
Unrealized Losses	(673)	(4,510)
Unrealized Gains Losses, Net	97,523	176,679
Contractual maturities of restricted and non-restricted marketable investment securities
Debt securities with contractual maturities within one year	266,000
Debt securities with contractual maturities extending longer than one year through and including five years	121,000
Debt securities with contractual maturities longer than ten years	93,000
Accumulated net unrealized gains (losses)
Accumulated net unrealized gains, before tax, in accumulated other comprehensive income (loss)	98,000	177,000
Accumulated net unrealized gains, net of tax, in accumulated other comprehensive income (loss)	62,000	175,000
US Treasury and agency securities
Components of our available-for-sale investments
Total marketable investment securities	82,124	58,254
Unrealized Gains (Losses) on Marketable Investment Securities
Unrealized Gains	2	7
Unrealized Losses	(135)	(11)
Unrealized Gains Losses, Net	(133)	(4)
Commercial paper
Components of our available-for-sale investments
Total marketable investment securities		68,556
Corporate securities
Components of our available-for-sale investments
Total marketable investment securities	349,897	1,496,044
Unrealized Gains (Losses) on Marketable Investment Securities
Unrealized Gains	29,370	72,918
Unrealized Losses	(480)	(153)
Unrealized Gains Losses, Net	28,890	72,765
Other (including restricted)
Components of our available-for-sale investments
Total marketable investment securities	47,847	192,607
Unrealized Gains (Losses) on Marketable Investment Securities
Unrealized Gains	73	1,293
Unrealized Losses	(17)
Unrealized Gains Losses, Net	56	1,293
Equity securities
Components of our available-for-sale investments
Total marketable investment securities	160,323	393,254
Unrealized Gains (Losses) on Marketable Investment Securities
Unrealized Gains	68,751	106,971
Unrealized Losses	(41)	(4,346)
Unrealized Gains Losses, Net	$ 68,710	$ 102,625