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Note 7. Cash, Cash Equivalents, and Marketable Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Cash and cash equivalents	$ 1,482,054,000	$ 1,325,072,000	$ 901,294,000	$ 605,619,000
Marketable securities	509,032,000us-gaap_AvailableForSaleSecurities	439,102,000us-gaap_AvailableForSaleSecurities
Total cash, cash equivalents, marketable securities, and investments	1,991,086,000us-gaap_InvestmentsAndCash	1,764,174,000us-gaap_InvestmentsAndCash
Available-for-sale securities, gross realized gains	200,000
Marketable securities, in loss position for 12 months or greater, estimated fair value	41,100,000	0
Foreign debt [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Marketable securities	462,731,000	364,046,000
Marketable securities, in loss position for 12 months or greater, estimated fair value	41,060,000	0
Foreign government obligations [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Marketable securities	0	25,115,000
Marketable securities, in loss position for 12 months or greater, estimated fair value		0
Time deposits [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Marketable securities	40,000,000	0
U.S. debt [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Marketable securities	2,800,000	46,439,000
Marketable securities, in loss position for 12 months or greater, estimated fair value		0
U.S. government obligations [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Marketable securities	3,501,000	3,502,000
Cash [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Cash and cash equivalents	1,480,452,000	1,322,183,000
Money Market Funds [Member]
Cash, Cash Equivalents, and Marketable Securities [Line Items]
Cash and cash equivalents	$ 1,602,000	$ 2,889,000