Net Income Per Common Share (Components Of Computation Of Basic And Diluted Net Income Per Common Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net Income Per Common Share [Abstract]
Net income	$ 45,170	$ 34,692
Series A and B preferred share dividends	(5,213)	(5,058)
Unvested stock award participation in earnings	(107)	(129)
Numerator for basic net income per common share	39,850	29,505
Weighted average common shares outstanding	89,980	71,639
Average unvested stock awards outstanding	(531)	(457)
Denominator for basic net income per common share	89,449	71,182
Basic net income per common share	$ 0.45	$ 0.41
Dividends on antidilutive convertible preferred shares	(5,138)	(4,983)
Unvested stock award participation in earnings	(107)	(129)
Numerator for diluted net income per common share	$ 39,925	$ 29,580
Net effect of dilutive stock and option awards	102	66
Net effect of dilutive convertible preferred shares	308	309
Denominator for diluted net income per common share	89,859	71,557
Diluted net income per common share	$ 0.44	$ 0.41