Shareholders' Equity (Reconciliation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 59,012	$ 63,898	$ 172,735	$ 176,872
Preferred Stock Dividends, Income Statement Impact	1,469	1,469	4,407	4,407
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	477	519	1,401	1,433
Net income attributable to common shareholders	$ 57,066	$ 61,910	$ 166,927	$ 171,032
Weighted average number of common shares outstanding - basic	165,762	165,389	165,638	165,263
Earnings Per Share, Basic	$ 0.34	$ 0.37	$ 1.01	$ 1.03
Net Income (Loss) Available to Common Stockholders, Diluted	$ 57,066	$ 61,910	$ 166,927	$ 171,032
Weighted average number of common shares outstanding - diluted	166,058	165,804	165,939	165,916
Earnings Per Share, Diluted	$ 0.34	$ 0.37	$ 1.01	$ 1.03
Employee Stock Option
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Weighted average number of common shares outstanding - diluted	296	415	301	653