Equity-Based Compensation Plans (Details 1) (USD $)	3 Months Ended
Mar. 31, 2013
Summary of stock option activity
Number of options, Beginning balance	3,752,418
Weighted Average Exercise Price, Beginning balance	$ 15.99
Number of Options, Granted	255,000
Weighted Average Exercise Price, Granted	$ 11.46
Number of Options, Exercised	(57,784)
Weighted Average Exercise Price, Exercised	$ 5.33
Number of Options, Cancelled	(41,983)
Weighted Average Exercise Price, Cancelled	$ 23.95
Number of options, Ending balance	3,907,651
Weighted Average Exercise Price, Ending balance	$ 15.77
Weighted Average Remaining Contractual Life-Years	4 years 10 months
Aggregate intrinsic value, Ending balance	$ 6,049,150
Number of Options, Exercisable options	2,639,703
Weighted Average Exercise Price, Exercisable options	$ 19.13
Weighted Average Remaining Contractual Term, Exercisable options	4 years 5 months
Aggregate Intrinsic Value, Exercisable options	$ 1,687,827

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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