Common Stock Issued and Outstanding (Activity in the Number of Common Stock Shares Issued and Outstanding) (Details) - shares		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Stockholders' Equity and Common Stock Issued and Outstanding [Abstract]
At beginning of year		172,202,177		172,034,711	177,499,513
Stock options exercised			[1]	0	15,575	[1]
Restricted stock awards	[1]	368,132		158,504	478,549
Employee stock purchase and thrift plans		2,564		8,962	8,387
Treasury shares purchased					(5,967,313)
At end of year		172,572,873		172,202,177	172,034,711

[1] Shares issued upon exercise of stock options and award of restricted stock are less than the amount reflected in Note J due to withholdings for statutory income taxes owed upon issuance of shares.