Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Cumulative perpetual preferred stock, par value (per share)	$ 0	$ 0
Cumulative perpetual preferred stock, shares authorized	100,000,000	100,000,000
Cumulative perpetual preferred stock, shares issued	967,870	967,870
Cumulative perpetual preferred stock, shares outstanding	967,870	967,870
Common stock, par value (per share)	$ 1	$ 1
Common stock, shares authorized	1,200,000,000	1,200,000,000
Common stock, shares issued	792,272,692	790,988,880
Common stock, shares outstanding	786,579,240	785,295,428
Treasury stock, shares at cost	5,693,452	5,693,452