Earnings Per Share Level 4 (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income attributable to common stockholders	$ 35,496	$ 18,765	$ 100,353	$ 89,962
After tax interest on convertible debt	13	0	38	38
Net income — diluted	$ 35,509	$ 18,765	$ 100,391	$ 90,000
Weighted average shares — basic	(232,917)	(246,214)	(237,037)	(250,762)
Stock options	2,475	1,309	2,370	1,603
Convertible debt	121	0	121	121
Weighted average shares — diluted	235,513	247,523	239,528	252,486
Net income attributable to common stockholders, basic	$ 0.15	$ 0.08	$ 0.42	$ 0.36
Net income attributable to common stockholders, diluted	$ 0.15	$ 0.08	$ 0.42	$ 0.36