Earnings per Share 1 (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share Basic And Diluted Summary [Abstract]
Net earnings from continuing operations									$ 255,424	$ 242,648	$ 179,580
Loss from discontinued operations					(18,100)	0	0	0	0	(18,100)	0
Preferred stock dividends									0	(5,040)	(8,683)
Loss on extinguishment of preferred stock									0	(3,295)	0
Net earnings available for common stockholders	$ 76,957	$ 58,032	$ 59,773	$ 60,662	$ 55,868	$ 36,632	$ 69,424	$ 54,289	$ 255,424	$ 216,213	$ 170,897
Weighted average shares outstanding - Basic									124,720	124,474	124,076
Weighted average shares outstanding - Diluted									126,283	125,191	124,409
Basic earnings per share:
Net earnings available for common stockholders from continuing operations					$ 0.59	$ 0.29	$ 0.56	$ 0.44	$ 2.05	$ 1.88	$ 1.38
Loss from discontinued operations									$ 0	$ (0.14)	$ 0
Net earnings available for common stockholders	$ 0.62	$ 0.47	$ 0.48	$ 0.49	$ 0.45	$ 0.29	$ 0.55	$ 0.43	$ 2.05	$ 1.74	$ 1.38
Diluted earnings per share:
Net earnings available for common stockholders from continuing operations					$ 0.59	$ 0.29	$ 0.56	$ 0.44	$ 2.02	$ 1.87	$ 1.37
Loss from discontinued operations									$ 0	$ (0.14)	$ 0
Net earnings available for common stockholders	$ 0.61	$ 0.46	$ 0.47	$ 0.48	$ 0.45	$ 0.29	$ 0.55	$ 0.43	$ 2.02	$ 1.73	$ 1.37