Consolidated Balance Sheets (Parenthetical) (unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	[1]
Amortized cost of available-for-sale securities	$ 374,740	$ 398,815
Fair value of held-to-maturity securities	$ 142,217	$ 145,185
Preferred stock, shares authorized (shares)	10,000,000	10,000,000
Common stock, shares authorized (shares)	2,500,000,000	2,500,000,000
Common stock, shares issued (shares)	24,298,640	24,292,646
Preferred stock, Series A [Member]
Preferred stock, par value (in dollars per share)	$ 10.00	$ 10.00
Preferred stock, shares issued (shares)	51,500	51,500
Preferred stock, shares outstanding (shares)	0	0
Preferred stock, Series B [Member]
Preferred stock, shares authorized (shares)	250,000	250,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0

[1] Derived from audited consolidated financial statements