Earnings Per Common Share (Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Basic EPS
Net income attributable to common stockholders	$ 16,876	$ 12,803	$ 18,797	$ 5,940	$ 24,664	$ 40,741	$ 42,698	$ 36,192	$ 55,045	$ 144,295	$ 50,365
Basic EPS, Weighted Average Shares (Denominator) (in shares)									116,162,000	105,846,000	97,967,000
Basic earnings per share attributable to common stockholders	$ 0.14	$ 0.11	$ 0.17	$ 0.05	$ 0.21	$ 0.40	$ 0.41	$ 0.35	$ 0.47	$ 1.36	$ 0.51
Effect of Dilutive Securities
Effect of stock options (in shares)									57,924	59,607
Effect of nonvested shares (in shares)									762,060	957,604	1,189,253
Effect of convertible debentures (in shares)									14,500,000		7,082,000
Diluted EPS
Net income attributable to common stockholders and assumed conversions									60,174	147,946
Diluted EPS, Weighted Average Shares (Denominator) (in shares)									131,441,000	113,946,000	99,209,000
Diluted earnings per share attributable to common stockholders	$ 0.13	$ 0.11	$ 0.17	$ 0.05	$ 0.21	$ 0.37	$ 0.39	$ 0.34	$ 0.46	$ 1.30	$ 0.51
1.875% convertible debentures [Member]
Effect of Dilutive Securities
Effect of convertible debentures, net of tax									2,355	3,651
Effect of convertible debentures (in shares)									7,082,000	7,082,000
Diluted EPS
Debt instrument, stated rate	1.875%								1.875%
1.75% convertible debentures [Member]
Effect of Dilutive Securities
Effect of convertible debentures, net of tax									$ 2,774	$ 0
Effect of convertible debentures (in shares)									7,377,000	0
Diluted EPS
Debt instrument, stated rate	1.75%								1.75%