Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Held-to-maturity, fair value	$ 728,479	$ 729,974
Preferred stock, without par value
Preferred stock, authorized shares	4,400,000	4,400,000
Common stock, without par value
Common stock, authorized shares	350,000,000	350,000,000
Common stock, issued shares	184,228,178	184,135,388
Common stock, outstanding shares	184,228,178	184,135,388