Shareholders' Equity (Reconciliation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 56,584	$ 59,519	$ 113,723	$ 112,974
Preferred Stock Dividends, Income Statement Impact	1,469	1,469	2,938	2,938
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	467	489	937	926
Net income attributable to common shareholders	$ 54,648	$ 57,561	$ 109,848	$ 109,110
Weighted average number of common shares outstanding - basic	165,736	165,335	165,574	165,198
Earnings Per Share, Basic	$ 0.33	$ 0.35	$ 0.66	$ 0.66
Net Income (Loss) Available to Common Stockholders, Diluted	$ 54,648	$ 57,561	$ 109,848	$ 109,110
Weighted average number of common shares outstanding - diluted	166,277	166,147	166,089	166,052
Earnings Per Share, Diluted	$ 0.33	$ 0.35	$ 0.66	$ 0.66
Employee Stock Option
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Weighted average number of common shares outstanding - diluted	541	812	515	854