Income Taxes	6 Months Ended
Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We file a consolidated federal income tax return, consolidated unitary tax returns in certain states and other separate state income tax returns for our subsidiary companies. The income tax provision for interim periods is generally determined based upon the expected effective income tax rate for the full year and the tax rate applicable to certain discrete transactions in the interim period. To determine the annual effective income tax rate, we must estimate both the total income (loss) before income tax for the full year and the jurisdictions in which that income (loss) is subject to tax. The actual effective income tax rate for the full year may differ from these estimates if income (loss) before income tax is greater than or less than what was estimated or if the allocation of income (loss) to jurisdictions in which it is taxed is different from the estimated allocations. We review and adjust our estimated effective income tax rate for the full year each quarter based upon our most recent estimates of income (loss) before income tax for the full year and the jurisdictions in which we expect that income will be taxed. The effective income tax rate for the six months ended June 30, 2017 and 2016, was 9% and 27%, respectively. The primary reasons for the difference between these rates and the U.S. federal statutory rate of 35% are the impact of state taxes, non-deductible expenses and excess tax benefits on share-based compensation ($2.4 million and $1.9 million in 2017 and 2016, respectively). Deferred tax assets relating to our state jurisdictions totaled $9.5 million at June 30, 2017, which includes the tax effect of state net operating loss carryforwards. We recognize state net operating loss carryforwards as deferred tax assets, subject to valuation allowances. At each balance sheet date, we estimate the amount of carryforwards that are not expected to be used prior to expiration of the carryforward period. The tax effect of the carryforwards that are not expected to be used prior to their expiration is included in the valuation allowance.

Income Taxes

We file a consolidated federal income tax return, consolidated unitary tax returns in certain states and other separate state income tax returns for our subsidiary companies.

The income tax provision for interim periods is generally determined based upon the expected effective income tax rate for the full year and the tax rate applicable to certain discrete transactions in the interim period. To determine the annual effective income tax rate, we must estimate both the total income (loss) before income tax for the full year and the jurisdictions in which that income (loss) is subject to tax. The actual effective income tax rate for the full year may differ from these estimates if income (loss) before income tax is greater than or less than what was estimated or if the allocation of income (loss) to jurisdictions in which it is taxed is different from the estimated allocations. We review and adjust our estimated effective income tax rate for the full year each quarter based upon our most recent estimates of income (loss) before income tax for the full year and the jurisdictions in which we expect that income will be taxed.

The effective income tax rate for the six months ended June 30, 2017 and 2016, was 9% and 27%, respectively. The primary reasons for the difference between these rates and the U.S. federal statutory rate of 35% are the impact of state taxes, non-deductible expenses and excess tax benefits on share-based compensation ($2.4 million and $1.9 million in 2017 and 2016, respectively).

Deferred tax assets relating to our state jurisdictions totaled $9.5 million at June 30, 2017, which includes the tax effect of state net operating loss carryforwards. We recognize state net operating loss carryforwards as deferred tax assets, subject to valuation allowances. At each balance sheet date, we estimate the amount of carryforwards that are not expected to be used prior to expiration of the carryforward period. The tax effect of the carryforwards that are not expected to be used prior to their expiration is included in the valuation allowance.