CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement Of Stockholders Equity [Abstract]
Cumulative Preferred Stock, par	$ 100	$ 100	$ 100	$ 100	$ 100
Cumulative Preferred Stock, authorized	400,000	400,000	400,000	400,000	400,000
Cumulative Preferred Stock, issued	0	0	0	0	0
Common Stock, par	$ 1.00	$ 1.00	$ 1.00	$ 1.00	$ 1.00
Common Stock, authorized	450,000,000	450,000,000	450,000,000	450,000,000	450,000,000
Common Stock, issued	195,040,149	194,920,155	195,040,149	194,920,155	194,616,470
Cash dividends, per share	$ 0.35	$ 0.3125	$ 1.325	$ 1.25	$ 3.675
Balance at end of year, shares of Common Stock	17,540,636	11,513,642	17,540,636	11,513,642	3,975,153