Common Share Capitalization (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 06, 2017
Common Stock Capitalization [Line Items]
Dividends (in usd per share)	$ 0.45	$ 0.50
Payments of Dividends	$ 14,821	$ 16,872
Common Shares Issued And Outstanding Upon Conversion of All Convertible Securities	32,845,754	33,624,917
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			1,700,000
Shares repurchased	130,488	163,033
Stock Repurchased and Retired During Period, Value	$ 2,052	$ 2,834
Stock Repurchases, Average Price Per Share	$ 15.73