Net Income Per Common Share	9 Months Ended
Sep. 30, 2011
Earnings Per Share [Abstract]
Net Income Per Common Share	Net Income Per Common Share For the purpose of computing diluted net income per share, the weighted-average number of shares outstanding is increased for the potential dilutive effects of stock-based incentive plans and convertible senior subordinated notes. For the purpose of computing diluted net income per share, the weighted-average number of shares was increased by 546,547 and 493,453 for the three-month periods ended September 30, 2011 and 2010, respectively, and 769,528 and 619,305 for the nine-month periods ended September 30, 2011 and 2010, respectively, to account for the potential dilutive effect of stock-based incentive plans. There were no adjustments to net income for the purposes of computing income available to common stockholders for those periods. The calculation of weighted-average diluted shares outstanding excludes all shares that would have been anti-dilutive. During the three-month periods ended September 30, 2011 and 2010, the Company excluded 686,016 and 2,340,018 stock options, respectively, from the calculation of weighted average diluted shares outstanding as the stock options would have been anti-dilutive. During the nine-month periods ended September 30, 2011 and 2010, the Company excluded 844,552 and 1,969,091 stock options, respectively, from the calculation of weighted average diluted shares outstanding as the stock options would have been anti-dilutive. The Company granted 379,900 stock options, 109,989 restricted stock unit awards and 79,500 performance share awards in February 2011 as part of its annual grant award. All of the stock options and the restricted stock unit awards vest upon meeting certain service conditions. The restricted stock unit awards are included in basic average common shares outstanding as they contain nonforfeitable rights to dividend payments. The performance share awards are part of a new long-term Relative Measure Program, which is designed to assess the long-term Company performance relative to the performance of companies included in the Russell 2000 Index. The performance goals are independent of each other and based on three metrics, the Company's total shareholder return ("TSR"), basic earnings per share growth and operating income before depreciation and amortization growth (weighted equally). The participants can earn from zero to 250% of the target award and the award includes a forfeitable right to dividend equivalents, which are not included in the aggregate target award numbers. The fair value of the TSR performance awards was determined using a Monte Carlo simulation as the award contains a market condition. Effective April 5, 2011, the Company, through the trustee of its 3.75% convertible senior subordinated notes due in August 2025 (the "3.75% Convertible Notes"), exercised its right to redeem the remaining $92,500 principal amount of these notes under their indenture agreement. Of the total $92,500 principal amount, $11,865 of these notes were redeemed with accrued interest through the redemption date. The remaining $80,635 of these notes were surrendered for conversion. The Company elected to pay cash to holders of the notes surrendered for conversion, including the value of any residual shares of common stock that were payable to the holders electing to convert their notes into an equivalent share value, resulting in a total cash payment of $90,438 including a premium on conversion of $9,803 which reduced the equity component by $6,085, net of tax of $3,718. As a result of this transaction, the Company recaptured $40,217 of previously deducted contingent convertible debt interest which resulted in a $15,252 reduction in short-term deferred tax liabilities as well as a reduction of tax loss carryforwards reflected in long-term deferred tax assets. The potential shares issuable for the 3.75% Convertible Notes were not included in either basic or diluted average common shares outstanding for the nine-month period ended September 30, 2011 as the notes were settled in cash. For the three- and nine-month periods ended September 30, 2010, there were no potential shares issuable under the notes as the notes would have been anti-dilutive under the net share settlement method. The 3.375% convertible senior subordinated notes due in March 2027 (the “3.375% Convertible Notes”) are convertible, under certain circumstances, into a combination of cash and common stock of the Company. The conversion price as of September 30, 2011 was approximately $28.31 per share of common stock. The dilutive effect of the notes is determined based on the average closing price of the Company's stock for the last 30 trading days of the quarter as compared to the conversion price of the notes. Under the net share settlement method, there were no potential shares issuable under the notes as the notes would have been anti-dilutive for the three- and nine-month periods ended September 30, 2011 and 2010.

Net Income Per Common Share

For the purpose of computing diluted net income per share, the weighted-average number of shares outstanding is increased for the potential dilutive effects of stock-based incentive plans and convertible senior subordinated notes. For the purpose of computing diluted net income per share, the weighted-average number of shares was increased by 546,547 and 493,453 for the three-month periods ended September 30, 2011 and 2010, respectively, and 769,528 and 619,305 for the nine-month periods ended September 30, 2011 and 2010, respectively, to account for the potential dilutive effect of stock-based incentive plans. There were no adjustments to net income for the purposes of computing income available to common stockholders for those periods.

The calculation of weighted-average diluted shares outstanding excludes all shares that would have been anti-dilutive. During the three-month periods ended September 30, 2011 and 2010, the Company excluded 686,016 and 2,340,018 stock options, respectively, from the calculation of weighted average diluted shares outstanding as the stock options would have been anti-dilutive. During the nine-month periods ended September 30, 2011 and 2010, the Company excluded 844,552 and 1,969,091 stock options, respectively, from the calculation of weighted average diluted shares outstanding as the stock options would have been anti-dilutive.

The Company granted 379,900 stock options, 109,989 restricted stock unit awards and 79,500 performance share awards in February 2011 as part of its annual grant award. All of the stock options and the restricted stock unit awards vest upon meeting certain service conditions. The restricted stock unit awards are included in basic average common shares outstanding as they contain nonforfeitable rights to dividend payments. The performance share awards are part of a new long-term Relative Measure Program, which is designed to assess the long-term Company performance relative to the performance of companies included in the Russell 2000 Index. The performance goals are independent of each other and based on three metrics, the Company's total shareholder return ("TSR"), basic earnings per share growth and operating income before depreciation and amortization growth (weighted equally). The participants can earn from zero to 250% of the target award and the award includes a forfeitable right to dividend equivalents, which are not included in the aggregate target award numbers. The fair value of the TSR performance awards was determined using a Monte Carlo simulation as the award contains a market condition.

Effective April 5, 2011, the Company, through the trustee of its 3.75% convertible senior subordinated notes due in August 2025 (the "3.75% Convertible Notes"), exercised its right to redeem the remaining $92,500 principal amount of these notes under their indenture agreement. Of the total $92,500 principal amount, $11,865 of these notes were redeemed with accrued interest through the redemption date. The remaining $80,635 of these notes were surrendered for conversion. The Company elected to pay cash to holders of the notes surrendered for conversion, including the value of any residual shares of common stock that were payable to the holders electing to convert their notes into an equivalent share value, resulting in a total cash payment of $90,438 including a premium on conversion of $9,803 which reduced the equity component by $6,085, net of tax of $3,718. As a result of this transaction, the Company recaptured $40,217 of previously deducted contingent convertible debt interest which resulted in a $15,252 reduction in short-term deferred tax liabilities as well as a reduction of tax loss carryforwards reflected in long-term deferred tax assets. The potential shares issuable for the 3.75% Convertible Notes were not included in either basic or diluted average common shares outstanding for the nine-month period ended September 30, 2011 as the notes were settled in cash. For the three- and nine-month periods ended September 30, 2010, there were no potential shares issuable under the notes as the notes would have been anti-dilutive under the net share settlement method.

The 3.375% convertible senior subordinated notes due in March 2027 (the “3.375% Convertible Notes”) are convertible, under certain circumstances, into a combination of cash and common stock of the Company. The conversion price as of September 30, 2011 was approximately $28.31 per share of common stock. The dilutive effect of the notes is determined based on the average closing price of the Company's stock for the last 30 trading days of the quarter as compared to the conversion price of the notes. Under the net share settlement method, there were no potential shares issuable under the notes as the notes would have been anti-dilutive for the three- and nine-month periods ended September 30, 2011 and 2010.