Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Securities held to maturity, fair value	$ 874,858	$ 889,733
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)	64,789,943	65,834,395
Common stock, outstanding (in shares)	64,789,943	65,834,395

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