FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified		3 Months Ended
	Dec. 31, 2013	Mar. 31, 2014 U.S. treasury bills	Mar. 31, 2014 Total	Dec. 31, 2013 Total	Mar. 31, 2014 Total Government securities money market	Dec. 31, 2013 Total Government securities money market	Mar. 31, 2014 Total U.S. treasury bills	Dec. 31, 2013 Total U.S. treasury bills	Mar. 31, 2014 Total Bank time deposits	Dec. 31, 2013 Total Bank time deposits	Dec. 31, 2013 Total Common Stock	Mar. 31, 2014 Level 2	Dec. 31, 2013 Level 2	Mar. 31, 2014 Level 2 Government securities money market	Dec. 31, 2013 Level 2 Government securities money market	Mar. 31, 2014 Level 2 U.S. treasury bills	Dec. 31, 2013 Level 2 U.S. treasury bills	Mar. 31, 2014 Level 2 Bank time deposits	Dec. 31, 2013 Level 2 Bank time deposits	Dec. 31, 2013 Level 3	Dec. 31, 2013 Level 3 Common Stock
Fair value measurements
Maximum investment term		6 months
Cash and cash equivalents					$ 77,006	$ 73,366	$ 119,480	$ 146,991	$ 40,484	$ 40,468				$ 77,006	$ 73,366	$ 119,480	$ 146,991	$ 40,484	$ 40,468
Total investments in securities	68,141			68,141				66,237			1,904		66,237				66,237			1,904	1,904
Total financial assets			$ 236,970	$ 328,966								$ 236,970	$ 327,062							$ 1,904