Income Taxes	6 Months Ended
Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	3. Income Taxes Income tax expense for the six months ended June 30, 2018 and 2017 has been computed using estimated annual effective tax rates. These rates reflect the change in the U.S. statutory tax rate from 35% to 21%, effective January 1, 2018. These rates are revised, if necessary, at the end of each successive interim period to reflect current estimates of the annual effective tax rates. For the six months ended June 30, 2018, the tax provision was comprised of a $25.7 million U.S. federal income tax expense and a $7.8 million foreign income tax expense. For the six months ended June 30, 2017, the tax provision was comprised of a $44.3 million U.S. federal income tax expense and a $2.1 million foreign income tax expense. The Company or its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state jurisdictions, as well as foreign jurisdictions. The Company and its subsidiaries are subject to U.S. federal and state income tax examinations and foreign examinations for years after 2013.

Income Taxes

6 Months Ended

Jun. 30, 2018

3. Income Taxes

Income tax expense for the six months ended June 30, 2018 and 2017 has been computed using estimated annual effective tax rates. These rates reflect the change in the U.S. statutory tax rate from 35% to 21%, effective January 1, 2018. These rates are revised, if necessary, at the end of each successive interim period to reflect current estimates of the annual effective tax rates.

For the six months ended June 30, 2018, the tax provision was comprised of a $25.7 million U.S. federal income tax expense and a $7.8 million foreign income tax expense. For the six months ended June 30, 2017, the tax provision was comprised of a $44.3 million U.S. federal income tax expense and a $2.1 million foreign income tax expense.

The Company or its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state jurisdictions, as well as foreign jurisdictions. The Company and its subsidiaries are subject to U.S. federal and state income tax examinations and foreign examinations for years after 2013.