INCOME TAXES	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income tax expense for the three months ended March 31, 2018, was $2.6 million, or 0.9% of income before taxes, compared with $21.3 million, or 10.5% of income before taxes, for the three months ended March 31, 2017. The effective tax rate for the three months ended March 31, 2018, differed from the U.S. federal statutory rate of 21% primarily due to excess tax benefits associated with employee equity plans and federal R&D credit benefits, partially offset by state income taxes. The effective tax rate for the three months ended March 31, 2017, differed from the U.S. federal statutory rate of 35% primarily due to excess tax benefits associated with employee equity plans, the effect of certain foreign earnings being taxed at rates lower than the federal statutory rate, and federal R&D credit benefit, partially offset by state income taxes. In connection with the Tax Act enacted in December 2017, the Company recorded a provisional amount of $317.8 million in its income tax expense for the year ended December 31, 2017. In accordance with relevant SEC guidance, the effects of the Tax Act may be adjusted within a one-year measurement period from the enactment date for items that were previously reported as provisional, or where a provisional estimate could not be made. Income tax provision for the three months ended March 31, 2018, did not reflect any adjustment to the previously assessed Tax Act enactment effect. Income tax expense for the three months ended March 31, 2018, reflected a $9.1 million estimate for the tax on global intangible low-taxed income enacted by the Tax Act. For the global intangible low-taxed income provisions of the Tax Act, the Company has not yet elected an accounting policy with respect to either recognize deferred taxes for basis differences expected to reverse as global intangible low-taxed income, or to record such as period costs if and when incurred. The Company will continue to assess forthcoming guidance and accounting interpretations on the effects of the Tax Act and expects to complete its analysis within the measurement period in accordance with the SEC guidance. As a result of the Tax Act, the Company can repatriate its cumulative undistributed foreign earnings back to the U.S. when, and if, needed with minimal additional tax consequences. As of March 31, 2018, the Company had a total of gross unrecognized tax benefits of $69.6 million compared with $65.4 million as of December 31, 2017, representing a net increase of approximately $4.2 million for the three months ended March 31, 2018. The net increase was primarily related to 2018 uncertain tax positions. If recognized, the gross unrecognized tax benefits would reduce the effective tax rate in the period of recognition. The Company files federal, state, and foreign income tax returns in many U.S. and OUS jurisdictions. Years before 2014 are closed for the significant jurisdictions. Certain of the Company’s unrecognized tax benefits could change due to activities of various tax authorities, including potential assessment of additional tax, possible settlement of audits, or through normal expiration of various statutes of limitations, which could affect the Company’s effective tax rate in the period in which they change. Due to the uncertainty related to the timing and potential outcome of audits, the Company cannot estimate the range of reasonably possible change in unrecognized tax benefits that may occur in the next 12 months. The Company is subject to the examination of its income tax returns by the Internal Revenue Service and other tax authorities. The outcome of these audits cannot be predicted with certainty. The Company's management regularly assesses the likelihood of adverse outcomes resulting from these examinations to determine the adequacy of the Company’s provision for income taxes. If any issues addressed in the Company’s tax audits are resolved in a manner not consistent with management’s expectations, the Company could be required to adjust its provision for income taxes in the period such resolution occurs.

INCOME TAXES

Income tax expense for the three months ended March 31, 2018, was $2.6 million, or 0.9% of income before taxes, compared with $21.3 million, or 10.5% of income before taxes, for the three months ended March 31, 2017. The effective tax rate for the three months ended March 31, 2018, differed from the U.S. federal statutory rate of 21% primarily due to excess tax benefits associated with employee equity plans and federal R&D credit benefits, partially offset by state income taxes. The effective tax rate for the three months ended March 31, 2017, differed from the U.S. federal statutory rate of 35% primarily due to excess tax benefits associated with employee equity plans, the effect of certain foreign earnings being taxed at rates lower than the federal statutory rate, and federal R&D credit benefit, partially offset by state income taxes.

In connection with the Tax Act enacted in December 2017, the Company recorded a provisional amount of $317.8 million in its income tax expense for the year ended December 31, 2017. In accordance with relevant SEC guidance, the effects of the Tax Act may be adjusted within a one-year measurement period from the enactment date for items that were previously reported as provisional, or where a provisional estimate could not be made. Income tax provision for the three months ended March 31, 2018, did not reflect any adjustment to the previously assessed Tax Act enactment effect. Income tax expense for the three months ended March 31, 2018, reflected a $9.1 million estimate for the tax on global intangible low-taxed income enacted by the Tax Act. For the global intangible low-taxed income provisions of the Tax Act, the Company has not yet elected an accounting policy with respect to either recognize deferred taxes for basis differences expected to reverse as global intangible low-taxed income, or to record such as period costs if and when incurred. The Company will continue to assess forthcoming guidance and accounting interpretations on the effects of the Tax Act and expects to complete its analysis within the measurement period in accordance with the SEC guidance. As a result of the Tax Act, the Company can repatriate its cumulative undistributed foreign earnings back to the U.S. when, and if, needed with minimal additional tax consequences.

As of March 31, 2018, the Company had a total of gross unrecognized tax benefits of $69.6 million compared with $65.4 million as of December 31, 2017, representing a net increase of approximately $4.2 million for the three months ended March 31, 2018. The net increase was primarily related to 2018 uncertain tax positions. If recognized, the gross unrecognized tax benefits would reduce the effective tax rate in the period of recognition.

The Company files federal, state, and foreign income tax returns in many U.S. and OUS jurisdictions. Years before 2014 are closed for the significant jurisdictions. Certain of the Company’s unrecognized tax benefits could change due to activities of various tax authorities, including potential assessment of additional tax, possible settlement of audits, or through normal expiration of various statutes of limitations, which could affect the Company’s effective tax rate in the period in which they change. Due to the uncertainty related to the timing and potential outcome of audits, the Company cannot estimate the range of reasonably possible change in unrecognized tax benefits that may occur in the next 12 months.

The Company is subject to the examination of its income tax returns by the Internal Revenue Service and other tax authorities. The outcome of these audits cannot be predicted with certainty. The Company's management regularly assesses the likelihood of adverse outcomes resulting from these examinations to determine the adequacy of the Company’s provision for income taxes. If any issues addressed in the Company’s tax audits are resolved in a manner not consistent with management’s expectations, the Company could be required to adjust its provision for income taxes in the period such resolution occurs.