Equity (Share Activity) (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2018	Mar. 31, 2018	Mar. 31, 2017
Equity, Treasury Stock [Line Items]
Payments for repurchase of common stock		$ 90,880,000	$ 0
2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value		$ 98,400,000
2016 Share Repurchase Program [Member] | Subsequent Event [Member]
Equity, Treasury Stock [Line Items]
Payments for repurchase of common stock	$ 8,000,000
2016 Share Repurchase Program [Member] | Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)		2,000,000
2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value		$ 100,000,000
2018 Share Repurchase Program [Member] | Subsequent Event [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value	$ 24,500,000
2018 Share Repurchase Program [Member] | Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)		0
2018 Share Repurchase Program [Member] | Treasury Stock, Common [Member] | Subsequent Event [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	600,000