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.

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Amount of excess tax benefit (tax deficiency) that arises when compensation cost from non-qualified share-based compensation recognized on the entity's tax return exceeds (is less than) compensation cost from equity-based compensation recognized in financial statements. Excess tax benefit (tax deficiency) increases (decreases) net cash provided by financing activities.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Share-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 1,667	$ 3,264	$ 5,106	$ 7,175
Excess Tax Benefit recognized for share-based compensation			2,944	1,213
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award
Shares granted			32,608
Weighted-average grant date fair value (in dollars per share)			$ 47.32
Vesting period of new awards granted (in years)			3 years
Fair value of shares vested			$ 643	$ 524