Note 13 - Fair Value Measurements and Disclosures (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jul. 31, 2011	Jan. 31, 2011	Jun. 30, 2013 $40 Million Secured Debt Facility [Member]	May 31, 2013 $40 Million Secured Debt Facility [Member]	Dec. 31, 2012 $40 Million Secured Debt Facility [Member]	Jan. 31, 2011 $40 Million Secured Debt Facility [Member]	Jun. 30, 2013 $75 Million Secured Debt Facility [Member]	Dec. 31, 2012 $75 Million Secured Debt Facility [Member]	Jul. 31, 2011 $75 Million Secured Debt Facility [Member]	Jun. 30, 2013 2015 Convertible Notes [Member]	Dec. 31, 2012 2015 Convertible Notes [Member]	Mar. 31, 2010 2015 Convertible Notes [Member]	Jun. 30, 2013 US Treasury Bill Securities [Member]
Note 13 - Fair Value Measurements and Disclosures (Details) [Line Items]
Debt Instrument, Face Amount					$ 75,000	$ 40,000	$ 40,000	$ 25,500	$ 40,000	$ 40,000	$ 75,000	$ 75,000	$ 75,000			$ 170,900
Held-to-maturity Securities, Fair Value	1,000	[1]	0														1,000
Convertible Debt, Fair Value Disclosures	$ 138,460	[2]	$ 147,861	[2]										$ 138,500	$ 147,900

[1] The Company estimated the fair value of the U.S. Treasury bill to be approximately $1.0 million at June 30, 2013, based on observed market prices for the same or similar types of debt issues. The fair value of the U.S. Treasury bill is considered to be a Level 2 measurement on the fair value hierarchy.

[2] The Company estimated the fair value of the $170.9 million 2015 Convertible Notes to be approximately $138.5 million and $147.9 million at June 30, 2013 and December 31, 2012, respectively, based on observed market prices for the same or similar types of debt issues. The fair value of the $170.9 million 2015 Convertible Notes is considered to be a Level 1 measurement on the fair value hierarchy.