Shareholders' Equity (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 31, 2016	Jun. 30, 2014
Shareholders' Equity (Textual)
Common stock authorized under repurchase program			$ 200,000,000	$ 300,000,000	$ 250,000,000
Stock repurchases, Shares	(2,400,000)	(1,900,000)	(1,400,000)
Payments for stock repurchases	$ (125,400,000)	$ (124,600,000)	$ (68,600,000)
Common stock, shares authorized	120,000,000	120,000,000
Common Stock, Par or Stated Value Per Share	$ 0.625	$ 0.625
Common stock, shares issued	66,776,290.000000	66,600,984
Common stock, shares outstanding	41,970,098	44,198,850
Series A and B $2.50 Cumulative Convertible Preferred Stock [Member]
Shareholders' Equity (Textual)
Preferred stock, shares authorized	5,000,000
Preferred stock, par value	$ 1.00
Preferred stock, shares outstanding		15,567
Cumulative annual cash dividend per share on preferred stock	$ 2.50