Equity Equity (Common Stock Changes in Number of Shares Issued, Held in Treasury and Oustanding) (Details) - shares		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758	79,137,758
Treasury Stock, Shares, Acquired		(208,680)	(1,356,892)	(4,145,440)
Common Stock Issuable [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758	79,137,758	79,137,758	79,137,758
Stock Based Compensation Shares	[1]	0	0	0
Treasury Stock, Shares, Acquired		0	0	0
Common Stock Held In Treasury [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		14,685,663	14,835,256	13,933,232	10,364,797
Stock Based Compensation Shares	[1]	(358,273)	(454,868)	(577,005)
Treasury Stock, Shares, Acquired		(208,680)	(1,356,892)	(4,145,440)
Common Stock Outstanding [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		64,452,095	64,302,502	65,204,526	68,772,961
Stock Based Compensation Shares	[1]	358,273	454,868	577,005
Treasury Stock, Shares, Acquired		(208,680)	(1,356,892)	(4,145,440)

[1] Represents net shares issued from treasury pursuant to the Company’s stock-based compensation programs.