Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Available-for-sale debt securities, amortized cost	$ 972,856	$ 940,212
Trading securities, debt, amortized cost	3,802	5,052
Available-for-sale equity securities, amortized cost	$ 74,508	$ 74,553
Common stock, par value (in dollars per share)	$ 0.0002	$ 0.0002
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	29,467,647	29,257,566
Common stock, shares outstanding	29,467,647	29,257,566
Preferred stock par value (in dollars per share)	$ 0.00125	$ 0.00125
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0