Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Held to maturity, estimated fair value	$ 487	$ 6,699
Common stock, par value	$ 2.5	$ 2.5
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	216,700,000	216,200,000
Treasury stock, shares	17,800,000	16,000,000