Equity (Share Activity) (Narrative) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 21, 2018	Sep. 11, 2018	Dec. 31, 2016
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value		$ 29,862,000	$ 98,400,000	$ 602,000	$ 128,311,000
Share repurchase program, amount available for future share repurchases, value	$ 128,800,000			128,800,000
September 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value							$ 150,000,000
Share repurchase program, amount available for future share repurchases, value	28,800,000			28,800,000
2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value								$ 100,000,000
March 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value			$ 100,000,000
December 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value						$ 100,000,000
Share repurchase program, amount available for future share repurchases, value	$ 100,000,000			$ 100,000,000
Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	0	664,218	2,000,000.0	15,100	2,702,938
Treasury stock acquired, value		$ 29,862,000		$ 602,000	$ 128,311,000