Income taxes	9 Months Ended
Sep. 30, 2012
Income taxes	10. Income taxes At the end of each interim period, the Company applies its estimated annual effective tax rate (“ETR”) to its interim earnings before considering the tax effect of any discrete items. The Company also records the tax impact of certain unusual or infrequently occurring items, including the effects of changes in valuation allowances and tax laws or rates, in the interim period in which they occur. Any penalties and/or interest incurred in connection with the payment of the Company’s income tax obligations are classified within general and administrative expenses and interest expense, respectively. The computation of the estimated annual ETR at each interim period requires certain estimates and significant judgments, including, but not limited to, the expected operating income for the year, projections of the proportion of income earned and taxed in state jurisdictions, permanent and temporary differences, and the likelihood of recovering deferred tax assets generated in the current year. The accounting estimates used to compute the provision for income taxes may change as new events occur, additional information is obtained, or the tax environment changes. For the 2012 fiscal year, the Company’s estimated annual ETR is 37.2%, excluding the impact of changes in the valuation of the Private Placement Warrants which is permanently excluded from taxable income. The Company’s ETR for the nine months ended September 30, 2012 was 34.5% compared with 37.1% for the comparable prior year period. The Company’s ETR in the nine months ended September 30, 2012 was lower due to the exclusion of $0.6 million of other income recognized in connection with the change in the valuation of the Private Placement Warrants. The income or expense associated with the change in the Private Placement Warrants is excluded from the computation of taxable income. Given the subjectivity and volatility of the valuation of the Private Placement Warrants, it is not possible to project the impact of the change in the Private Placement Warrants in the computation of the Company’s estimated annual ETR. As a result, the Company’s estimated annual ETR is impacted by the changes in the valuation of the Private Placement Warrants in the periods in which such changes occur.

Income taxes

9 Months Ended

Sep. 30, 2012

10. Income taxes

At the end of each interim period, the Company applies its estimated annual effective tax rate (“ETR”) to its interim earnings before considering the tax effect of any discrete items. The Company also records the tax impact of certain unusual or infrequently occurring items, including the effects of changes in valuation allowances and tax laws or rates, in the interim period in which they occur. Any penalties and/or interest incurred in connection with the payment of the Company’s income tax obligations are classified within general and administrative expenses and interest expense, respectively.

The computation of the estimated annual ETR at each interim period requires certain estimates and significant judgments, including, but not limited to, the expected operating income for the year, projections of the proportion of income earned and taxed in state jurisdictions, permanent and temporary differences, and the likelihood of recovering deferred tax assets generated in the current year. The accounting estimates used to compute the provision for income taxes may change as new events occur, additional information is obtained, or the tax environment changes. For the 2012 fiscal year, the Company’s estimated annual ETR is 37.2%, excluding the impact of changes in the valuation of the Private Placement Warrants which is permanently excluded from taxable income.

The Company’s ETR for the nine months ended September 30, 2012 was 34.5% compared with 37.1% for the comparable prior year period. The Company’s ETR in the nine months ended September 30, 2012 was lower due to the exclusion of $0.6 million of other income recognized in connection with the change in the valuation of the Private Placement Warrants. The income or expense associated with the change in the Private Placement Warrants is excluded from the computation of taxable income. Given the subjectivity and volatility of the valuation of the Private Placement Warrants, it is not possible to project the impact of the change in the Private Placement Warrants in the computation of the Company’s estimated annual ETR. As a result, the Company’s estimated annual ETR is impacted by the changes in the valuation of the Private Placement Warrants in the periods in which such changes occur.