Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Amortized cost of available-for-sale securities	$ 473,438	$ 430,836
Common stock, no par value
Common stock, shares authorized	2,500,000,000	2,500,000,000
Common stock, shares issued	21,587,880	21,102,668
Preferred stock Series A [Member]
Preferred stock, par value	$ 10	$ 10
Preferred stock, shares authorized	200,000	200,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock [Member]
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0