Earnings Per Share Level 4 (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income attributable to common stockholders	$ 26,779	$ 41,062	$ 118,015	$ 126,163
After tax interest on convertible debt	13	13	38	38
Net income — diluted	$ 26,792	$ 41,075	$ 118,053	$ 126,201
Weighted average shares — basic	(211,954)	(214,914)	(211,721)	(216,974)
Stock options	4,295	3,425	4,035	3,211
Convertible debt	121	121	121	121
Weighted average shares — diluted	216,370	218,460	215,877	220,306
Net income attributable to common stockholders, basic	$ 0.13	$ 0.19	$ 0.56	$ 0.58
Net income attributable to common stockholders, diluted	$ 0.12	$ 0.19	$ 0.55	$ 0.57