Income Taxes	3 Months Ended
Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income taxes Our effective tax rate for the three months ended March 31, 2016 and 2015 was 29.5%, and 42.6%, respectively. Our effective tax rate for the current year differed from the federal statutory tax rate primarily due to the favorable resolution of certain state income tax matters. For the prior year, our effective tax rate differed from the federal statutory tax rate primarily due to state income taxes and an adjustment to deferred taxes due to changes in state laws and business operations. At March 31, 2016 and December 31, 2015, we had deferred tax assets, net of deferred tax liabilities and valuation allowance, of $1.3 billion and $1.4 billion, respectively. The accounting for deferred taxes is based upon estimates of future results. Differences between estimated and actual results could result in changes in the valuation of deferred tax assets that could have a material impact on our consolidated results of operations or financial position. Changes in existing tax laws could also affect actual tax results and the realization of deferred tax assets over time. Unrecognized tax benefits represent the difference between tax positions taken or expected to be taken in a tax return and the benefits recognized for financial statement purposes. At March 31, 2016 and December 31, 2015, we had $22.5 million and $39.0 million, respectively, of gross unrecognized tax benefits and $11.8 million and $17.2 million, respectively, of related accrued interest and penalties. It is reasonably possible within the next twelve months that our gross unrecognized tax benefits may decrease by up to $18.5 million, excluding interest and penalties, primarily due to expirations of certain statutes of limitations and potential settlements. We are currently under examination by the IRS and various state taxing jurisdictions and anticipate finalizing certain examinations within the next twelve months. The final outcome of these examinations is not yet determinable. The statutes of limitation for our major tax jurisdictions generally remain open for examination for tax years 2005 to 2016.

Income Taxes

3 Months Ended

Mar. 31, 2016

Income taxes

Our effective tax rate for the three months ended March 31, 2016 and 2015 was 29.5%, and 42.6%, respectively. Our effective tax rate for the current year differed from the federal statutory tax rate primarily due to the favorable resolution of certain state income tax matters. For the prior year, our effective tax rate differed from the federal statutory tax rate primarily due to state income taxes and an adjustment to deferred taxes due to changes in state laws and business operations.

At March 31, 2016 and December 31, 2015, we had deferred tax assets, net of deferred tax liabilities and valuation allowance, of $1.3 billion and $1.4 billion, respectively. The accounting for deferred taxes is based upon estimates of future results. Differences between estimated and actual results could result in changes in the valuation of deferred tax assets that could have a material impact on our consolidated results of operations or financial position. Changes in existing tax laws could also affect actual tax results and the realization of deferred tax assets over time.

Unrecognized tax benefits represent the difference between tax positions taken or expected to be taken in a tax return and the benefits recognized for financial statement purposes. At March 31, 2016 and December 31, 2015, we had $22.5 million and $39.0 million, respectively, of gross unrecognized tax benefits and $11.8 million and $17.2 million, respectively, of related accrued interest and penalties. It is reasonably possible within the next twelve months that our gross unrecognized tax benefits may decrease by up to $18.5 million, excluding interest and penalties, primarily due to expirations of certain statutes of limitations and potential settlements.

We are currently under examination by the IRS and various state taxing jurisdictions and anticipate finalizing certain examinations within the next twelve months. The final outcome of these examinations is not yet determinable. The statutes of limitation for our major tax jurisdictions generally remain open for examination for tax years 2005 to 2016.