Earnings Per Share Level 4 (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income attributable to common stockholders	$ 26,093	$ 40,285	$ 64,857	$ 71,197
After tax interest on convertible debt	13	13	25	25
Net income — diluted	$ 26,106	$ 40,298	$ 64,882	$ 71,222
Weighted average shares — basic	(238,498)	(251,763)	(239,131)	(253,074)
Stock options	2,816	1,699	2,337	1,667
Convertible debt	121	121	121	121
Weighted average shares — diluted	241,435	253,583	241,589	254,862
Net income attributable to common stockholders, basic	$ 0.11	$ 0.16	$ 0.27	$ 0.28
Net income attributable to common stockholders, diluted	$ 0.11	$ 0.16	$ 0.27	$ 0.28