Income Taxes	9 Months Ended
Sep. 30, 2017
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Taxes	Income Taxes We have historically calculated our provision for income taxes during interim reporting periods by applying the estimated annual effective tax rate for the full fiscal year to pre-tax income or loss, excluding discrete items, for the reporting period. We determined that since small changes in estimated pre-tax income or loss would result in significant changes in our estimated annual effective tax rate, the historical method utilized would not provide a reliable estimate of income taxes for the three-month and nine-month periods ended September 30, 2017. We used a discrete effective tax rate method to calculate income taxes for the three-month and nine-month periods ended September 30, 2017. We will continue to evaluate income tax estimates under the historical method in subsequent quarters and employ a discrete effective tax rate method if warranted. Discrete income tax expense for the three-month period ended September 30, 2017 was $3.2 million and resulted primarily from a rig sale and resolutions of prior year tax matters. Discrete income tax expense for the nine-month period ended September 30, 2017 was $13.0 million and resulted primarily from the Exchange Offers and debt repurchases, rig sales, a restructuring transaction, settlement of a previously disclosed legal contingency, the effective settlement of a liability for unrecognized tax benefits associated with a tax position taken in prior years and other resolutions of prior year tax matters. Our consolidated effective income tax rate for the three-month and nine-month periods ended September 30, 2016, excluding the impact of discrete tax items, was 6.0% and 21.9%, respectively. Net discrete income tax benefits for the three-month and nine-month periods ended September 30, 2016 of $6.0 million and $1.6 million, respectively, were primarily attributable to the gain on debt extinguishment, changes in liabilities for unrecognized tax benefits associated with tax positions taken in prior years and other resolutions of prior year matters. Discrete tax items for the nine-month period ended September 30, 2016 also resulted from restructuring transactions involving certain of our subsidiaries.

Income Taxes

We have historically calculated our provision for income taxes during interim reporting periods by applying the estimated annual effective tax rate for the full fiscal year to pre-tax income or loss, excluding discrete items, for the reporting period. We determined that since small changes in estimated pre-tax income or loss would result in significant changes in our estimated annual effective tax rate, the historical method utilized would not provide a reliable estimate of income taxes for the three-month and nine-month periods ended September 30, 2017. We used a discrete effective tax rate method to calculate income taxes for the three-month and nine-month periods ended September 30, 2017. We will continue to evaluate income tax estimates under the historical method in subsequent quarters and employ a discrete effective tax rate method if warranted.

Discrete income tax expense for the three-month period ended September 30, 2017 was $3.2 million and resulted primarily from a rig sale and resolutions of prior year tax matters. Discrete income tax expense for the nine-month period ended September 30, 2017 was $13.0 million and resulted primarily from the Exchange Offers and debt repurchases, rig sales, a restructuring transaction, settlement of a previously disclosed legal contingency, the effective settlement of a liability for unrecognized tax benefits associated with a tax position taken in prior years and other resolutions of prior year tax matters.

Our consolidated effective income tax rate for the three-month and nine-month periods ended September 30, 2016, excluding the impact of discrete tax items, was 6.0% and 21.9%, respectively. Net discrete income tax benefits for the three-month and nine-month periods ended September 30, 2016 of $6.0 million and $1.6 million, respectively, were primarily attributable to the gain on debt extinguishment, changes in liabilities for unrecognized tax benefits associated with tax positions taken in prior years and other resolutions of prior year matters. Discrete tax items for the nine-month period ended September 30, 2016 also resulted from restructuring transactions involving certain of our subsidiaries.