Marketable Securities, Available-for-sale (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011 D	Dec. 31, 2010	Dec. 31, 2009
Marketable Securities, Available-for-sale
Minimum original maturity of time deposits and short-term pooled investments, which are not considered cash equivalents (in days)	90
Gain from marketable securities, net	$ 3,882	$ 5,774	$ 3,725
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	348,628	437,688
GROSS UNREALIZED GAINS	269	426
GROSS UNREALIZED LOSSES	(1,881)	(319)
ESTIMATED FAIR VALUE	347,016	437,795
Total debt securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	322,853	332,526
GROSS UNREALIZED GAINS	269	424
GROSS UNREALIZED LOSSES	(1,881)	(319)
ESTIMATED FAIR VALUE	321,241	332,631
U.S. Treasury securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	1,557	15,782
GROSS UNREALIZED GAINS	0	81
GROSS UNREALIZED LOSSES	(2)	0
ESTIMATED FAIR VALUE	1,555	15,863
Obligations of U.S. and local government agencies
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	147,557	33,247
GROSS UNREALIZED GAINS	123	12
GROSS UNREALIZED LOSSES	(860)	(215)
ESTIMATED FAIR VALUE	146,820	33,044
Corporate debt securities issued under U.S. government/agency-backed programs
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	1,453	170,878
GROSS UNREALIZED GAINS	3	112
GROSS UNREALIZED LOSSES	0	0
ESTIMATED FAIR VALUE	1,456	170,990
Corporate debt securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	126,088	104,976
GROSS UNREALIZED GAINS	101	218
GROSS UNREALIZED LOSSES	(523)	(92)
ESTIMATED FAIR VALUE	125,666	105,102
Asset-backed securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	46,198	7,643
GROSS UNREALIZED GAINS	42	1
GROSS UNREALIZED LOSSES	(496)	(12)
ESTIMATED FAIR VALUE	45,744	7,632
Time deposits
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	25,500	76,312
GROSS UNREALIZED GAINS	0	0
GROSS UNREALIZED LOSSES	0	0
ESTIMATED FAIR VALUE	25,500	76,312
Short-term pooled investments
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	275	28,850
GROSS UNREALIZED GAINS	0	2
GROSS UNREALIZED LOSSES	0	0
ESTIMATED FAIR VALUE	$ 275	$ 28,852

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15E

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 14

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details