Share-Based Compensation and Employee Benefit Plans (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total compensation cost recognized	$ 5,900,000	$ 8,100,000	$ 8,000,000
Share-Based Compensation and Employee Benefit Plans (Textual) [Abstract]
Plan reserves issuance of shares	4,400,000
Shares available to be granted under plan	1,500,000
Stock option retroactive correction issuance of additional options	514,000
Stock option retroactive correction reduction of exercise price per option	$2.00 to $4.00
Term of options	10 years
Options outstanding, aggregate intrinsic value	7,100,000
Options outstanding, Weighted average remaining contractual term	3.0
Options exercisable, aggregate intrinsic value	1,400,000
Options exercisable, Weighted average remaining contractual term	2.6
Intrinsic value of stock options exercised	3,000,000	2,900,000
Recognized tax benefits			0
Aggregate fair value of shares that vested	6,100,000	4,400,000	3,100,000
Total compensation cost capitalized	500,000	800,000	1,300,000
Total unvested compensation cost not yet recognized	7,400,000
Unvested compensation cost weighted average period	1.8
Authorize payroll deductions	15.00%
Minimum period of service as eligible criteria of employees under condition one	30 days
Minimum age of employee as eligible criteria of employees under condition two	18 years
Shares purchased under Employee Stock Purchase Plan	3,681	5,662	20,076
Average price purchased shares	$ 24.04	$ 20.92	$ 8.82
Discount rate of compensation to purchase shares	5.00%
Incurred costs in connection with this plan	100,000	100,000	600,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vest period, minimum	one to four years
Options vest period, maximum	5 years
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vest period, minimum	3 years
Options vest period, maximum	5 years
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total compensation cost recognized	$ 0