Shareholders' Equity Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average common and common stock equivalent shares outstanding	109,689,000	109,211,000
Net income	$ 37,346	$ 30,344
Dividends, Preferred Stock	930	0
Undistributed Earnings Allocated to Participating Securities	291	137
Net income available to common shareholders	36,125	30,207
Average Common Shares Outstanding Prior to Participating Share Adjustment	110,807,000	110,041,000
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	1,118,000	830,000
Weighted average number of common shares outstanding - basic	109,689,000	109,211,000
Earnings Per Share, Basic	$ 0.33	$ 0.28
Income used in diluted earnings per share calculation	$ 36,125	$ 30,207
Weighted average number of shares outstanding prior to participating share adjustment	110,807,000	110,041,000
Earnings Per Share, Diluted	$ 0.33	$ 0.28
Options to Purchase Shares	1,600,000	2,300,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average common and common stock equivalent shares outstanding	0	0