Stock-based Compensation Plans	6 Months Ended
Stock-based Compensation Plans	Jun. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-based Compensation Plans Stock-based Compensation Cost Total stock-based compensation cost recognized in the condensed consolidated statements of operations as a component of selling, general and administrative expenses was $1.4 million and $1.3 million for the three months ended June 30, 2013 and 2012, respectively, and $2.7 million for both the six months ended June 30, 2013 and 2012. Total unrecognized compensation cost related to non-vested share-based compensation arrangements was $10.1 million at June 30, 2013. This balance is expected to be recognized over a weighted-average period of 2.1 years. Total unrecognized compensation cost may be adjusted for any unearned performance shares or forfeited shares. Grant Activities During the first six months of 2013, we granted 87,268 restricted stock units to employees and non-employee directors from the 2010 Long Term Incentive Plan (“LTIP”) at a weighted-average grant date fair value of $49.38, compared to 81,468 restricted stock units from the 2010 LTIP at a weighted-average grant date fair value of $39.67 for the same period in 2012. During the first six months of 2013, we also granted 90,500 performance-based shares to employees from the 2010 LTIP at a weighted-average grant date fair value of $49.13, compared to 85,252 performance-based shares to employees from the 2010 LTIP at the weighted-average grant date fair value of $39.59 for the same period in 2012. The 90,500 performance shares granted during 2013 represent the maximum that can be earned. The number of performance shares that the employee ultimately earns is based upon achievement of certain specified performance metrics during 2013. The 2013 grants generally vest over a three-year period with one-third vesting twelve months following the date of grant, one-third vesting in January 2015 and the remaining one-third vesting in January 2016. The weighted-average grant date fair value is based on the fair market value of our common stock at the date of grant.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

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