Marketable Securities, Available-for-sale (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Marketable Securities, Available-for-sale
Gain from marketable securities, net	$ 2,214	$ 3,882	$ 5,774
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	387,477	348,628
GROSS UNREALIZED GAINS	1,278	269
GROSS UNREALIZED LOSSES	(735)	(1,881)
ESTIMATED FAIR VALUE	388,020	347,016
Total debt securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	350,350	322,853
GROSS UNREALIZED GAINS	1,278	269
GROSS UNREALIZED LOSSES	(728)	(1,881)
ESTIMATED FAIR VALUE	350,900	321,241
U.S. Treasury securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	3,098	1,557
GROSS UNREALIZED GAINS	1	0
GROSS UNREALIZED LOSSES	0	(2)
ESTIMATED FAIR VALUE	3,099	1,555
Obligations of U.S. and local government agencies
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	154,774	147,557
GROSS UNREALIZED GAINS	1,008	123
GROSS UNREALIZED LOSSES	(489)	(860)
ESTIMATED FAIR VALUE	155,293	146,820
Corporate debt securities issued under U.S. government/agency-backed programs
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	0	1,453
GROSS UNREALIZED GAINS	0	3
GROSS UNREALIZED LOSSES	0	0
ESTIMATED FAIR VALUE	0	1,456
Corporate debt securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	165,153	126,088
GROSS UNREALIZED GAINS	116	101
GROSS UNREALIZED LOSSES	(75)	(523)
ESTIMATED FAIR VALUE	165,194	125,666
Asset-backed securities
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	27,325	46,198
GROSS UNREALIZED GAINS	153	42
GROSS UNREALIZED LOSSES	(164)	(496)
ESTIMATED FAIR VALUE	27,314	45,744
Time deposits
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	0	25,500
GROSS UNREALIZED GAINS	0	0
GROSS UNREALIZED LOSSES	0	0
ESTIMATED FAIR VALUE	0	25,500
Short-term pooled investments
Schedule of fair values of available-for-sale marketable securities
AMORTIZED COST	37,127	275
GROSS UNREALIZED GAINS	0	0
GROSS UNREALIZED LOSSES	(7)	0
ESTIMATED FAIR VALUE	$ 37,120	$ 275

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Publisher FASB

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+ 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