Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Statement of Financial Position [Abstract]
Held to maturity, estimated fair value	$ 6,774	$ 7,818
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	216,000,000	215,400,000
Treasury stock, shares	16,100,000	16,300,000