Debt	6 Months Ended
Jun. 30, 2015
Debt Disclosure [Abstract]
Debt	Debt We have $275 million of 3.875% senior notes due 2021 (the “2021 Notes”) and $275 million of 4.375% senior notes due 2024 (the “2024 Notes”), with interest payable semi-annually. The 2021 Notes were sold at 99.5% of the principal amount with an effective yield of 3.951%. The 2024 Notes were sold at 99.6% of the principal with an effective yield of 4.422%. We have the option to redeem the 2021 Notes and 2024 Notes in part or in whole prior to maturity at a redemption price equal to the greater of 100% of the principal amount or the present value of the remaining scheduled payments discounted at the Treasury Rate plus 30 basis points. As of June 30, 2015 and December 31, 2014, the estimated fair value of the 2021 Notes was $280.7 million and $275.1 million and the estimated fair value of the 2024 Notes was $279.7 million and $283.9 million, respectively. We have a Credit Agreement with a $450 million borrowing capacity which extends through September 2019. Under the Amended Credit Agreement, we have the ability to request two one-year extensions and to request an increase in aggregate commitments by up to $200 million. The interest rate on the Amended Credit Agreement, which is subject to adjustment quarterly, is based on the London Interbank Offered Rate (LIBOR), the Federal Funds Rate or the Prime Rate, plus an adjustment based on the better of our debt ratings or leverage ratio (Credit Spread) as defined by the Amended Credit Agreement. We are charged a commitment fee of between 12.5 and 25.0 basis points on the unused portion of the facility. The terms of the Amended Credit Agreement limit the amount of indebtedness that we may incur and require us to maintain ratios for leverage and interest coverage, including on a pro forma basis in the event of an acquisition. Based on our leverage ratio at June 30, 2015, the interest rate under the credit facility is LIBOR plus 1.375%. At June 30, 2015, we had no borrowings and letters of credit of approximately $5.0 million outstanding under the Amended Credit Agreement, leaving $445 million available for borrowing. We also have a $1.2 million letter of credit outstanding as of June 30, 2015 and December 31, 2014, which supports our facilities leased in Europe. The Amended Credit Agreement and senior notes contain cross-default provisions which could result in the acceleration of payments due in the event of default of either agreement. We believe we were in compliance with our debt covenants at June 30, 2015.

Debt

We have $275 million of 3.875% senior notes due 2021 (the “2021 Notes”) and $275 million of 4.375% senior notes due 2024 (the “2024 Notes”), with interest payable semi-annually. The 2021 Notes were sold at 99.5% of the principal amount with an effective yield of 3.951%. The 2024 Notes were sold at 99.6% of the principal with an effective yield of 4.422%. We have the option to redeem the 2021 Notes and 2024 Notes in part or in whole prior to maturity at a redemption price equal to the greater of 100% of the principal amount or the present value of the remaining scheduled payments discounted at the Treasury Rate plus 30 basis points. As of June 30, 2015 and December 31, 2014, the estimated fair value of the 2021 Notes was $280.7 million and $275.1 million and the estimated fair value of the 2024 Notes was $279.7 million and $283.9 million, respectively.

We have a Credit Agreement with a $450 million borrowing capacity which extends through September 2019. Under the Amended Credit Agreement, we have the ability to request two one-year extensions and to request an increase in aggregate commitments by up to $200 million. The interest rate on the Amended Credit Agreement, which is subject to adjustment quarterly, is based on the London Interbank Offered Rate (LIBOR), the Federal Funds Rate or the Prime Rate, plus an adjustment based on the better of our debt ratings or leverage ratio (Credit Spread) as defined by the Amended Credit Agreement. We are charged a commitment fee of between 12.5 and 25.0 basis points on the unused portion of the facility. The terms of the Amended Credit Agreement limit the amount of indebtedness that we may incur and require us to maintain ratios for leverage and interest coverage, including on a pro forma basis in the event of an acquisition. Based on our leverage ratio at June 30, 2015, the interest rate under the credit facility is LIBOR plus 1.375%.

At June 30, 2015, we had no borrowings and letters of credit of approximately $5.0 million outstanding under the Amended Credit Agreement, leaving $445 million available for borrowing. We also have a $1.2 million letter of credit outstanding as of June 30, 2015 and December 31, 2014, which supports our facilities leased in Europe.

The Amended Credit Agreement and senior notes contain cross-default provisions which could result in the acceleration of payments due in the event of default of either agreement. We believe we were in compliance with our debt covenants at June 30, 2015.