Equity (Share Activity) (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 19, 2020	Dec. 21, 2018	Sep. 11, 2018
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	0	3,600,000
Treasury stock acquired, value		$ 119,426,000
Stock repurchase program, remaining authorized repurchase amount	$ 158,600,000
September 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)		600,000
Treasury stock acquired, value		$ 28,800,000
Share repurchase program, amount authorized, value					$ 150,000,000
December 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)		3,000,000.0
Treasury stock acquired, value		$ 90,600,000
Share repurchase program, amount authorized, value				$ 100,000,000
Stock repurchase program, remaining authorized repurchase amount	8,600,000
March 2020 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value			$ 150,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 150,000,000