Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Held-to-maturity Securities, Fair Value	$ 6,699	$ 7,818
Statement of Financial Position [Abstract]
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	216,200,000	215,400,000
Treasury stock, shares	16,000,000	16,300,000