Common Share Capitalization (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Common Stock Capitalization [Line Items]
Dividends (in usd per share)	$ 0.65	$ 0.77	$ 1.30	$ 1.54
Payments of Dividends	$ 22,200	$ 20,100	$ 44,318	$ 40,140
Common Shares Issued And Outstanding Upon Conversion of All Convertible Securities	34,090,992	26,064,802	34,090,992	26,064,802