Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Available-for-sale debt securities, amortized cost (in dollars)	$ 897,445	$ 737,916
Trading securities, debt, amortized cost (in dollars)	5,053	7,324
Available-for-sale equity securities, amortized cost (in dollars)	$ 69,830	$ 64,348
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	28,941,547	28,540,350
Common stock, shares outstanding	28,941,547	28,540,350
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