Shareholders' Equity (Details Textual) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 25, 2019
Shareholders' Equity (Textual)
Common stock authorized under repurchase program					$ 300,000,000
Stock repurchases, Shares		2,000,000.0	1,500,000	1,700,000
Payments for stock repurchases	$ (100,000,000.0)	$ (150,000,000.0)	$ (115,500,000)	$ (100,000,000.0)
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		67,500,000	67,329,081
Common stock, shares outstanding		34,800,000	36,612,227
Series A and B $2.50 Cumulative Convertible Preferred Stock [Member]
Shareholders' Equity (Textual)
Preferred stock, shares authorized		5,000,000,000,000
Preferred stock, par value		$ 1.00