Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Amortized cost of available-for-sale securities	$ 438,057	$ 558,818
Fair value of held-to-maturity securities	$ 141,125
Preferred stock, shares outstanding		0
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	2,500,000,000	2,500,000,000
Common stock, shares issued	21,861,418	21,698,115
Preferred stock Series A [Member]
Preferred stock, par value	$ 10.00	$ 10.00
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	$ 1.00	$ 1.00
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0