Shareholders' Equity (Reconciliation of Basic and Diluted EPS) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 57,139us-gaap_NetIncomeLoss	$ 53,455us-gaap_NetIncomeLoss
Preferred Stock Dividends, Income Statement Impact	1,469	1,469
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	407	380
Net income attributable to common shareholders	55,263	51,606
Weighted average number of common shares outstanding - basic	165,411	165,060
Earnings Per Share, Basic	$ 0.33us-gaap_EarningsPerShareBasic	$ 0.31us-gaap_EarningsPerShareBasic
Net Income (Loss) Available to Common Stockholders, Diluted	$ 55,263	$ 51,606
Weighted average number of common shares outstanding - diluted	166,003	166,004
Earnings Per Share, Diluted	$ 0.33us-gaap_EarningsPerShareDiluted	$ 0.31us-gaap_EarningsPerShareDiluted
Employee Stock Option
Schedule of Earnings Per Share, Basic and Diluted [Line Items]
Weighted average number of common shares outstanding - diluted	592	944

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