Investments (Details)	6 Months Ended
	Jun. 30, 2014
Contract maturity of available-for-sale securities [Abstract]
One year or less (in hundredths)	53.00%
After one year but within two years (in hundredths)	36.00%
After two years but within three years (in hundredths)	11.00%
Total (in hundredths)	100.00%
Percentage of available-for-sale securities with a maturity of less than two years (in hundredths)	89.00%
Ownership interests in private and public companies [Abstract]
Number of privately-held companies in which the entity has an equity ownership interest of less than 20%	2
Number of publicly-held companies in which the entity has an equity ownership interest of less than 20%	4
Maximum [Member]
Ownership interests in private and public companies [Abstract]
Equity investments not classified as equity method, ownership percentage (in hundredths)	20.00%