|3 Months Ended|
Mar. 31, 2019
|Income Tax Disclosure [Abstract]|
|Income Tax||Income TaxOur effective tax rate may vary from the U.S. federal statutory tax rate due to the change in the mix of earnings in various state jurisdictions with different statutory rates, benefits related to tax credits, and the tax impact of non-deductible expenses, stock award activities and other permanent differences between income before income taxes and taxable income. The effective tax rate for the three months ended March 31, 2019 and March 31, 2018 was 20.9% and 18.1%, respectively. The variance from the U.S. federal statutory tax rate of 21% for the three months ended March 31, 2019 was primarily attributable to tax deductions related to stock award activities which were recorded as discrete items. The variance from the U.S. federal statutory tax rate of 21% for the three months ended March 31, 2018 was primarily attributable to tax deductions related to stock award activities which were recorded as discrete items in the quarter as well as the release of a valuation allowance relating to our investment in Viking.|
The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef