Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Short-term Debt [Line Items]
Net income attributable to common stockholders	$ 18,200	$ 42,698	$ 20,639	$ 78,890
Convertible debentures excluded	994	994		1,987
Income available to common stockholders + assumed conversions	$ 19,194	$ 43,692		$ 80,877
Weighted Average Number of Shares Outstanding, Basic	115,819,000	103,037,000	115,686,000	102,688,000
1.875% Convertible debentures	7,082,000	7,082,000		7,082,000
Stock option weighted shares of common stock	48,919	78,418	63,643	96,671
Incremental Common Shares Attributable to Nonvested Shares with Forfeitable Dividends	905,205	925,254	922,280	1,057,452
Weighted Average Number of Shares Outstanding, Diluted	123,855,000	111,123,000	116,671,000	110,924,000
Basic EPS (in usd per share)	$ 0.16	$ 0.41	$ 0.18	$ 0.77
Diluted EPS (in usd per share)	$ 0.15	$ 0.39	$ 0.18	$ 0.73
Convertible Debt Securities [Member]
Short-term Debt [Line Items]
Debt instrument interest rate	1.875%	1.875%	1.875%	1.875%