Income Taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company recorded a provision for income taxes of $6.2 million and $4.3 million for the three months ended September 30, 2017 and 2016, respectively, and $16.1 million and $14.9 million for the nine months ended September 30, 2017 and 2016, respectively. The income taxes for the three and nine months ended September 30, 2017 is primarily comprised of the Company's U.S. federal, state and foreign taxes and income tax expense recognized from exercises and expiration of out-of-the-money fully vested shares from equity incentive plans. Similarly, the income taxes for the three and nine months ended September 30, 2016 was primarily comprised of the Company's U.S. federal, state and foreign taxes and income tax expense recognized from exercises and expiration of shares from equity incentive plans. During the three and nine months ended September 30, 2017, the Company paid withholding taxes of $4.7 million and $15.6 million, respectively. During the three and nine months ended September 30, 2016, the Company paid withholding taxes of $5.5 million and $16.5 million, respectively. As of September 30, 2017, the Company’s unaudited condensed consolidated balance sheets included net deferred tax assets, before valuation allowance, of approximately $225.0 million, which consists of net operating loss carryovers, tax credit carryovers, amortization, employee stock-based compensation expenses and certain liabilities, partially reduced by deferred tax liabilities associated with the convertible notes. The Company has U.S. federal deferred tax assets related to research and development credits, foreign tax credits and other tax attributes that can be used to offset federal taxable income in future periods. These credit carryforwards will expire if they are not used within certain time periods. As of September 30, 2017, the Company determined that there is sufficient positive evidence to conclude that it is more likely than not sufficient taxable income will exist in the future allowing the Company to recognize these deferred tax assets. It is possible that some or all these attributes could ultimately expire unused. If facts and circumstances change in the future, the Company may determine at that time a valuation allowance is necessary. A valuation allowance would materially increase the Company's tax expense in the period applied and would adversely affect its results of operations and statements of financial condition. Changes in the Company's underlying facts or circumstances, such as the impact of the acquisitions, will be continually assessed and the Company will re-evaluate its position accordingly. As of September 30, 2017, the Company continues to maintain a valuation allowance against the majority of its state deferred tax assets. Management periodically evaluates the realizability of the Company's net deferred tax assets based on all available evidence, both positive and negative. The realizability of the Company's net deferred tax assets is dependent on its ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. The Company continues to maintain a deferred tax asset valuation allowance of $29.0 million as of September 30, 2017. The Company maintains liabilities for uncertain tax positions within its long-term income taxes payable accounts and as a reduction to existing deferred tax assets to the extent tax attributes are available to offset such liabilities. These liabilities involve judgment and estimation and are monitored by management based on the best information available including changes in tax regulations, the outcome of relevant court cases and other information. As of September 30, 2017, the Company had approximately $22.9 million of unrecognized tax benefits, including $20.7 million recorded as a reduction of long-term deferred tax assets and $2.2 million in long-term income taxes payable. If recognized, approximately $2.2 million would be recorded as an income tax benefit. As of December 31, 2016, the Company had $21.9 million of unrecognized tax benefits, including $19.7 million recorded as a reduction of long-term deferred tax assets and $2.2 million recorded in long-term income taxes payable. Although it is possible that some of the unrecognized tax benefits could be settled within the next 12 months, the Company cannot reasonably estimate the outcome at this time. The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision. At September 30, 2017 and December 31, 2016, an immaterial amount of interest and penalties is included in long-term income taxes payable. Rambus files income tax returns for the U.S., California, India, the U.K., the Netherlands and various other state and foreign jurisdictions. The U.S. federal returns are subject to examination from 2014 and forward. The California returns are subject to examination from 2010 and forward. In addition, any research and development credit carryforward or net operating loss carryforward generated in prior years and utilized in these or future years may also be subject to examination. The India returns are subject to examination from fiscal year ending March 2012 and forward. The Company is currently under examination by California for the 2010 and 2011 tax years and New York for the 2013, 2014 and 2015 tax years. The Company’s India subsidiary is under examination by the Indian tax administration for tax years beginning with 2011, except for 2014, which was assessed in the Company's favor. These examinations may result in proposed adjustments to the income taxes as filed during these periods. Management regularly assesses the likelihood of outcomes resulting from income tax examinations to determine the adequacy of their provision for income taxes and believes their provision for unrecognized tax benefits is adequate. Additionally, the Company's future effective tax rates could be adversely affected by earnings being higher than anticipated in countries where the Company has higher statutory rates or lower than anticipated in countries where it has lower statutory rates, by changes in valuation of its deferred tax assets and liabilities or by changes in tax laws or interpretations of those laws.

Income Taxes

The Company recorded a provision for income taxes of $6.2 million and $4.3 million for the three months ended September 30, 2017 and 2016, respectively, and $16.1 million and $14.9 million for the nine months ended September 30, 2017 and 2016, respectively. The income taxes for the three and nine months ended September 30, 2017 is primarily comprised of the Company's U.S. federal, state and foreign taxes and income tax expense recognized from exercises and expiration of out-of-the-money fully vested shares from equity incentive plans. Similarly, the income taxes for the three and nine months ended September 30, 2016 was primarily comprised of the Company's U.S. federal, state and foreign taxes and income tax expense recognized from exercises and expiration of shares from equity incentive plans.

During the three and nine months ended September 30, 2017, the Company paid withholding taxes of $4.7 million and $15.6 million, respectively. During the three and nine months ended September 30, 2016, the Company paid withholding taxes of $5.5 million and $16.5 million, respectively.

As of September 30, 2017, the Company’s unaudited condensed consolidated balance sheets included net deferred tax assets, before valuation allowance, of approximately $225.0 million, which consists of net operating loss carryovers, tax credit carryovers, amortization, employee stock-based compensation expenses and certain liabilities, partially reduced by deferred tax liabilities associated with the convertible notes.

The Company has U.S. federal deferred tax assets related to research and development credits, foreign tax credits and other tax attributes that can be used to offset federal taxable income in future periods. These credit carryforwards will expire if they are not used within certain time periods. As of September 30, 2017, the Company determined that there is sufficient positive evidence to conclude that it is more likely than not sufficient taxable income will exist in the future allowing the Company to recognize these deferred tax assets. It is possible that some or all these attributes could ultimately expire unused. If facts and circumstances change in the future, the Company may determine at that time a valuation allowance is necessary. A valuation allowance would materially increase the Company's tax expense in the period applied and would adversely affect its results of operations and statements of financial condition. Changes in the Company's underlying facts or circumstances, such as the impact of the acquisitions, will be continually assessed and the Company will re-evaluate its position accordingly.

As of September 30, 2017, the Company continues to maintain a valuation allowance against the majority of its state deferred tax assets. Management periodically evaluates the realizability of the Company's net deferred tax assets based on all available evidence, both positive and negative. The realizability of the Company's net deferred tax assets is dependent on its ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. The Company continues to maintain a deferred tax asset valuation allowance of $29.0 million as of September 30, 2017.

The Company maintains liabilities for uncertain tax positions within its long-term income taxes payable accounts and as a reduction to existing deferred tax assets to the extent tax attributes are available to offset such liabilities. These liabilities involve judgment and estimation and are monitored by management based on the best information available including changes in tax regulations, the outcome of relevant court cases and other information.

As of September 30, 2017, the Company had approximately $22.9 million of unrecognized tax benefits, including $20.7 million recorded as a reduction of long-term deferred tax assets and $2.2 million in long-term income taxes payable. If recognized, approximately $2.2 million would be recorded as an income tax benefit. As of December 31, 2016, the Company had $21.9 million of unrecognized tax benefits, including $19.7 million recorded as a reduction of long-term deferred tax assets and $2.2 million recorded in long-term income taxes payable.

Although it is possible that some of the unrecognized tax benefits could be settled within the next 12 months, the Company cannot reasonably estimate the outcome at this time.

The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision. At September 30, 2017 and December 31, 2016, an immaterial amount of interest and penalties is included in long-term income taxes payable.

Rambus files income tax returns for the U.S., California, India, the U.K., the Netherlands and various other state and foreign jurisdictions. The U.S. federal returns are subject to examination from 2014 and forward. The California returns are subject to examination from 2010 and forward. In addition, any research and development credit carryforward or net operating loss carryforward generated in prior years and utilized in these or future years may also be subject to examination. The India returns are subject to examination from fiscal year ending March 2012 and forward. The Company is currently under examination by California for the 2010 and 2011 tax years and New York for the 2013, 2014 and 2015 tax years. The Company’s India subsidiary is under examination by the Indian tax administration for tax years beginning with 2011, except for 2014, which was assessed in the Company's favor. These examinations may result in proposed adjustments to the income taxes as filed during these periods. Management regularly assesses the likelihood of outcomes resulting from income tax examinations to determine the adequacy of their provision for income taxes and believes their provision for unrecognized tax benefits is adequate.

Additionally, the Company's future effective tax rates could be adversely affected by earnings being higher than anticipated in countries where the Company has higher statutory rates or lower than anticipated in countries where it has lower statutory rates, by changes in valuation of its deferred tax assets and liabilities or by changes in tax laws or interpretations of those laws.