Note 4 - Marketable Securities (Details) - Bond maturities by period (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Bond maturities by period [Abstract]
June 30, 2013	$ 11,399	$ 12,307
June 30, 2013	2,155
June 30, 2013	8,026
June 30, 2013	1,218
June 30, 2013	$ 0