Earnings (Loss) Per Share Data (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
Earnings (loss) per common share - Basic:
Income from continuing operations	$ 59,018	$ 61,425	$ 18,692	$ 55,739	$ 38,312	$ 37,784	$ 36,281	$ 49,155	$ 194,874	$ 161,532	$ 14,464
Loss from discontinued operations	0	0	0		(7,129)	(9,900)	(37,728)	(19,851)	0	(74,608)	(120,573)
Net income (loss)	59,018	61,425	18,692	55,739	31,183	27,884	(1,447)	29,304	194,874	86,924	(106,109)
Common shares (in shares)	106,773,000	109,315,000	110,580,000	111,487,000	111,687,000	112,729,000	113,487,000	114,129,000	109,531,000	113,000,000	116,348,000
Basic earnings per share, continuing operations (per share)	$ 0.55	$ 0.56	$ 0.17	$ 0.50	$ 0.34	$ 0.34	$ 0.32	$ 0.43	$ 1.78	$ 1.43	$ 0.12
Basic earnings per share, discontinued operations (per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.06)	$ (0.09)	$ (0.33)	$ (0.17)	$ 0.00	$ (0.66)	$ (1.04)
Earnings Per Share, Basic	$ 0.55	$ 0.56	$ 0.17	$ 0.50	$ 0.28	$ 0.25	$ (0.01)	$ 0.26	$ 1.78	$ 0.77	$ (0.91)
Effect of Dilutive Securities [Abstract]
Stock options, warrants and awards									0	0	0
Interest Income Convertible Securities									284	287	289
convertible debentures, common shares (in shares)									2,891,000	1,011,000	275,000
Stock options, warrants and awards, common shares (in shares)									566,000	770,000	304,000
Diluted EPS [Abstract]
Loss from discontinued operations	0	0	0		(7,129)	(9,900)	(37,728)	(19,851)	0	(74,608)	(120,573)
Net income plus assumed conversions									195,158	87,211	(105,820)
Diluted shares (in shares)	110,074,000	111,951,000	113,472,000	116,500,000	114,344,000	114,644,000	114,701,000	115,064,000	112,988,000	114,781,000	116,927,000
Diluted earnings per share, continuing operations plus assumed conversions (per share)	$ 0.54	$ 0.55	$ 0.17	$ 0.48	$ 0.34	$ 0.33	$ 0.32	$ 0.43	$ 1.73	$ 1.41	$ 0.13
Diluted earnings per share, discontinued operations (per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.06)	$ (0.09)	$ (0.33)	$ (0.17)	$ 0.00	$ (0.65)	$ (1.03)
Earnings Per Share, Diluted	$ 0.54	$ 0.55	$ 0.17	$ 0.48	$ 0.27	$ 0.24	$ (0.01)	$ 0.26	$ 1.73	$ 0.76	$ (0.91)
Income from continuing operations plus assumed conversions									$ 195,158	$ 161,819	$ 14,753
Aggregate number of stock options, warrants and awards excluded from the computation of diluted EPS (in shares)									2,100,000	2,600,000	4,600,000
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Diluted EPS [Abstract]
treasury stock method average share price to include dilutive securities									$ 27.19
Junior Subordinated Convertible Debentures [Member]
Diluted EPS [Abstract]
treasury stock method average share price to include dilutive securities									$ 40.82
3.25% Convertible Senior Debentures, Due 2035 [Member]
Diluted EPS [Abstract]
treasury stock method average share price to include dilutive securities									$ 78.74
3.75% Convertible Senior Subordinated Notes Due 2042 [Member]
Diluted EPS [Abstract]
treasury stock method average share price to include dilutive securities									$ 41.33