Income taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income taxes	Income taxes We recorded income tax expense of $3,321 for the three months ended September 30, 2017 and an income tax benefit of $848 for the three months ended September 30, 2016 which primarily consisted of foreign income taxes. For the nine months ended September 30, 2017 we recorded income tax expense of $4,465 and for the nine months ended September 30, 2016 we recorded an income tax benefit of $3,237. Our income tax benefit or expense is based on an annual effective tax rate forecast, including estimates and assumptions that could change during the year. The application of the accounting requirements for income taxes in interim periods, after consideration of our valuation allowance, causes a significant variation in the typical relationship between income tax expense and pretax accounting income. As of September 30, 2017, all of Century's U.S. and certain foreign deferred tax assets, net of deferred tax liabilities, continue to be subject to a valuation allowance.

Income taxes

9 Months Ended

Sep. 30, 2017

We recorded income tax expense of $3,321 for the three months ended September 30, 2017 and an income tax benefit of $848 for the three months ended September 30, 2016 which primarily consisted of foreign income taxes. For the nine months ended September 30, 2017 we recorded income tax expense of $4,465 and for the nine months ended September 30, 2016 we recorded an income tax benefit of $3,237.

Our income tax benefit or expense is based on an annual effective tax rate forecast, including estimates and assumptions that could change during the year. The application of the accounting requirements for income taxes in interim periods, after consideration of our valuation allowance, causes a significant variation in the typical relationship between income tax expense and pretax accounting income.

As of September 30, 2017, all of Century's U.S. and certain foreign deferred tax assets, net of deferred tax liabilities, continue to be subject to a valuation allowance.