Income Taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Spok files a consolidated U.S. Federal income tax return and income tax returns in various state, local and foreign jurisdictions as required. At September 30, 2017, we had total deferred income tax assets ("DTAs") of $72.0 million and no valuation allowance. This reflects a change from the December 31, 2016 balance of DTAs of $73.1 million and no valuation allowance. The change from December 31, 2016 to September 30, 2017 reflects the expected usage of the DTAs to offset expected 2017 taxable income and changes in tax rates. We consider both positive and negative evidence when evaluating the recoverability of our DTAs. The assessment is required to determine whether based on all available evidence, it is more likely than not (i.e., greater than a 50% probability) whether all or some portion of the DTAs will be realized in the future. During the fourth quarter of each year, we update our multi-year forecast of taxable income for our operations which assists in analyzing the recoverability of our DTAs. The anticipated effective income tax rate is expected to continue to differ from the Federal statutory rate of 35% primarily due to the effect of state income taxes, research and development credits, permanent differences between book and taxable income and certain discrete items. Our investment in research and development qualifies for the research and development income tax credit under Section 41 of the Internal Revenue code. Unused research and development tax credits have a 20-year carryover and will provide future tax benefits once Spok’s net operating losses are fully utilized. Of the total $1.3 million credit, $0.1 million relates to 2015, $0.3 million relates to 2016, and the remaining amount relates to 2017. As of January 1, 2017, we had approximately $126 million of Federal Net Operating Losses ("NOLs") available to offset future taxable income.

INCOME TAXES

Spok files a consolidated U.S. Federal income tax return and income tax returns in various state, local and foreign jurisdictions as required.

At September 30, 2017, we had total deferred income tax assets ("DTAs") of $72.0 million and no valuation allowance. This reflects a change from the December 31, 2016 balance of DTAs of $73.1 million and no valuation allowance. The change from December 31, 2016 to September 30, 2017 reflects the expected usage of the DTAs to offset expected 2017 taxable income and changes in tax rates.

We consider both positive and negative evidence when evaluating the recoverability of our DTAs. The assessment is required to determine whether based on all available evidence, it is more likely than not (i.e., greater than a 50% probability) whether all or some portion of the DTAs will be realized in the future. During the fourth quarter of each year, we update our multi-year forecast of taxable income for our operations which assists in analyzing the recoverability of our DTAs.

The anticipated effective income tax rate is expected to continue to differ from the Federal statutory rate of 35% primarily due to the effect of state income taxes, research and development credits, permanent differences between book and taxable income and certain discrete items.

Our investment in research and development qualifies for the research and development income tax credit under Section 41 of the Internal Revenue code. Unused research and development tax credits have a 20-year carryover and will provide future tax benefits once Spok’s net operating losses are fully utilized. Of the total $1.3 million credit, $0.1 million relates to 2015, $0.3 million relates to 2016, and the remaining amount relates to 2017.

As of January 1, 2017, we had approximately $126 million of Federal Net Operating Losses ("NOLs") available to offset future taxable income.