Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Equity [Abstract]
Treasury shares, acquired, tax burden	8,404		22,832
Treasury shares, acquired, value, tax burden	$ 800		$ 2,500
Treasury Stock, Shares, Acquired			77,832
Treasury Stock, Value, Acquired, Cost Method			$ 8,200
Treasury Stock, Value	$ 80,481		$ 80,481		$ 80,773
Stock Issued During Period, Shares, Treasury Stock Reissued	27,453		73,855
Cash dividends per share (in dollars per share)	$ 0.55	$ 0.55	$ 1.65	$ 1.65
Dividends declared (in dollars per share)	$ 0.55