Balance Sheet Components (Cash Cash Equivalents and Short Term and Long Term Investments) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents	$ 654,096	$ 278,823	$ 297,872	$ 442,841
Total marketable securities	168,925	797,522
Total cash, cash equivalents and short-term and long-term investments	823,021	1,076,345
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents	636,708	74,101
Money Markets [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents	17,388	198,931
Certificates Of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents		4,500
Total marketable securities	12,882	24,472
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents		1,000
Total marketable securities	995
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash and cash equivalents		291
Total marketable securities	18,075	64,308
U.S. Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	82,147	573,277
US Government Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	54,586	129,235
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities		5,283
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	$ 240	$ 947