Stockholders' Equity (Changes To Equity) (Details) - shares		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Common Shares Outstanding [Roll Forward]
Common shares outstanding at January 1		177,407,622	177,345,266	180,234,388
Issuance of restricted stock, excluding restricted stock with performance feature		0	55,626	870,378
Vesting of performance units		115,596	138,374	76,404
Vesting of restricted stock with performance feature		543,396	350,063	40,294
Forfeitures of restricted stock		(58,497)	(139,634)	(16,795)
Purchase of treasury stock	[1]	(5,886,626)	(342,073)	(3,859,403)
Common shares outstanding at December 31		172,121,491	177,407,622	177,345,266
Shares withheld for the payment of taxes		369,255	342,073	147,922

[1] Includes 369,255, 342,073 and 147,922 shares, respectively, withheld under the terms of stock-based compensation agreements to provide funds for the payment of payroll and income taxes due at the vesting of share-based awards, as well as other stock repurchases under separate authority from our Board of Directors.