Equity (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 25, 2016
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value	$ 1,551,000		$ 100,000,000
Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	38,807		5,217,693
Treasury stock acquired, value	$ 1,551,000		$ 100,000,000
2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value				$ 100,000,000
Treasury stock acquired, value	$ 1,600,000
2016 Share Repurchase Program [Member] | Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	38,800	0
2014 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value			$ 100,000,000
2014 Share Repurchase Program [Member] | Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)			5,200,000