Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets
Securities held to maturity, fair value	$ 78,096	$ 46,888
Shareholders' Equity
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	250,000,000	250,000,000
Common stock, issued (in shares)	67,151,087	64,820,414
Common stock, outstanding (in shares)	67,151,087	64,820,414