Equity (Common Stock Changes In Number of Shares Issued, Held In Treasury and Outstanding) (Details) - shares		3 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common Stock, Shares, Issued		79,137,758		79,137,758
Treasury Stock, Shares, Acquired		200,000
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
Treasury Stock, Shares, Acquired		0	0
Stock Based Compensation Shares	[1]	0	0
Common Stock Held In Treasury [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		14,769,487	14,931,485	14,835,256	13,933,232
Treasury Stock, Shares, Acquired		208,680	1,356,892
Stock Based Compensation Shares	[1]	(274,449)	(358,639)
Common Stock Outstanding [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued		64,368,271	64,206,273	64,302,502	65,204,526
Treasury Stock, Shares, Acquired		(208,680)	(1,356,892)
Stock Based Compensation Shares	[1]	(274,449)	(358,639)

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