Incentive Plans (Changes in Stock Options Outstanding) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Exercised	(21,200)	[1]	0	0
Outstanding at end of year	3,994,595
Exercisable at end of year	3,182,345
Stock Options [Member]
Number of Shares
Outstanding at beginning of year	4,901,269		5,757,435	5,443,288
Granted at FMV			603,000	862,000
Exercised	(72,000)
Forfeited	(834,674)		(1,459,166)	(547,853)
Outstanding at end of year	3,994,595		4,901,269	5,757,435
Exercisable at end of year	3,182,345		3,197,269	3,830,535	3,542,352
Average Exercise Price
Outstanding at beginning of year	$ 45.74		$ 48.46	$ 52.93
Granted at FMV			28.51	17.57
Exercised	17.57
Forfeited	53.36		49.34	44.23
Outstanding at end of year	44.66		45.74	48.46
Exercisable at end of year	$ 49.10		$ 54.22	$ 53.80	$ 52.26

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