Stocked Based Compensation Summary (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Stock-based compensation expense	$ 4,349	$ 1,955	$ 6,951	$ 3,901
Income tax benefit	(1,661)	(744)	(2,655)	(1,486)
Net expense	$ 2,688	$ 1,211	$ 4,296	$ 2,415

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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