Income Taxes	6 Months Ended
Jun. 30, 2016
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 June 30, 2016, we had total deferred income tax assets of $125.4 million and a valuation allowance of $45.8 million resulting in an estimated recoverable amount of deferred income tax assets of $79.6 million. This reflects a change from the December 31, 2015 balance of deferred income tax assets of $129.8 million and a valuation allowance of $45.8 million resulting in an estimated recoverable amount of $84.0 million. The change from December 31, 2015 to June 30, 2016 reflects the expected usage of the deferred income tax assets to offset expected 2016 taxable income and changes in tax rates. We consider both positive and negative evidence when evaluating the recoverability of our deferred income tax assets. 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 deferred income tax assets will be realized in the future. During the fourth quarter of each year, we prepare a multi-year forecast of taxable income for our operations. 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, the effect of changes to the deferred income tax asset valuation allowance, permanent differences between book and taxable income and certain discrete items. As of June 30, 2016, we had approximately $272.1 million of Federal net operating losses (“NOLs”) available to offset future taxable income. Section 382 of the Internal Revenue Code limited NOLs, as of June 30, 2016, were $35.0 million which may be used at a rate of $6.1 million per year, and is included in the total Federal NOLs.

Income Taxes

6 Months Ended

Jun. 30, 2016

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 June 30, 2016, we had total deferred income tax assets of $125.4 million and a valuation allowance of $45.8 million resulting in an estimated recoverable amount of deferred income tax assets of $79.6 million. This reflects a change from the December 31, 2015 balance of deferred income tax assets of $129.8 million and a valuation allowance of $45.8 million resulting in an estimated recoverable amount of $84.0 million. The change from December 31, 2015 to June 30, 2016 reflects the expected usage of the deferred income tax assets to offset expected 2016 taxable income and changes in tax rates.

We consider both positive and negative evidence when evaluating the recoverability of our deferred income tax assets. 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 deferred income tax assets will be realized in the future. During the fourth quarter of each year, we prepare a multi-year forecast of taxable income for our operations.

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, the effect of changes to the deferred income tax asset valuation allowance, permanent differences between book and taxable income and certain discrete items.

As of June 30, 2016, we had approximately $272.1 million of Federal net operating losses (“NOLs”) available to offset future taxable income. Section 382 of the Internal Revenue Code limited NOLs, as of June 30, 2016, were $35.0 million which may be used at a rate of $6.1 million per year, and is included in the total Federal NOLs.