Cash and Cash Equivalents and Short-term Investments (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013
Cash and cash equivalents and short-term investments
Cash and cash equivalents, fair value	$ 524,922	$ 389,915
Short-term investments:
Trading equity securities, fair value	52,705	3,200
Trading equity securities, gross unrealized holding gains	46,981
Available-for-sale equities securities
Available-for-sale equity securities, fair value	200,577	117,218
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	25,967	20,276
Available-for-sale securities, gross unrealized holding gains	139,205	72,530
Available-for-sale securities, gross unrealized holding losses	(1,225)	(56)
Total short-term investments	253,282	117,218
Total cash, cash equivalents and short-term investments, fair value	778,204	507,133
Total cash, cash equivalents and short-term investments, gross unrealized gains	186,186	72,530
Total cash, cash equivalents and short-term investments, gross unrealized losses	(1,225)	(56)
Available-for-sale equity securities
Available-for-sale equities securities
Available-for-sale equity securities, fair value	174,610	96,942
Available-for-sale debt securities:
Available-for-sale securities, gross unrealized holding gains	137,282	68,395
Available-for-sale securities, gross unrealized holding losses	(1,030)
Available-for-sale debt securities
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	25,967	20,276
Available-for-sale securities, gross unrealized holding gains	1,923	4,135
Available-for-sale securities, gross unrealized holding losses	(195)	(56)
Commercial paper and CDs
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	206
Corporate debt securities
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	23,399	19,388
Available-for-sale securities, gross unrealized holding gains	1,870	4,122
Mortgage-backed debt securities
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	244	210
Available-for-sale securities, gross unrealized holding gains	15	11
Mortgage-CMO debt securities
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	523	20
Available-for-sale securities, gross unrealized holding gains	10
Available-for-sale securities, gross unrealized holding losses	(3)	(2)
Asset-backed debt securities
Available-for-sale debt securities:
Total available-for-sale debt securities, fair value	1,595	658
Available-for-sale securities, gross unrealized holding gains	28	2
Available-for-sale securities, gross unrealized holding losses	(192)	(54)
Total Short-term investments
Available-for-sale debt securities:
Total short-term investments	253,282	117,218
Total short-term investments, gross unrealized gains	186,186	72,530
Total short-term investments, gross unrealized holding losses	$ (1,225)	$ (56)