Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	4. Income Taxes Income tax expense for the nine months ended September 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 and recomputed income to exclude discontinued Chaucer business. These rates are revised, if necessary, at the end of each successive interim period to reflect current estimates of the annual effective tax rates. The tax provision was comprised of U.S. federal income tax expense of $44.5 million and $53.4 million for the nine months ended September 30, 2018 and 2017, respectively. The tax provision recorded in discontinued operations related to discontinued Chaucer business for the nine months ended September 30, 2018 was comprised of a $0.2 million U.S. federal income tax benefit and a $6.8 million foreign income tax expense. For the nine months ended September 30, 2017, the tax provision recorded in discontinued operations was comprised of a $6.1 million U.S. federal income tax expense and a $16.5 million foreign income tax benefit. 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 2014.

4. Income Taxes

Income tax expense for the nine months ended September 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 and recomputed income to exclude discontinued Chaucer business. These rates are revised, if necessary, at the end of each successive interim period to reflect current estimates of the annual effective tax rates.

The tax provision was comprised of U.S. federal income tax expense of $44.5 million and $53.4 million for the nine months ended September 30, 2018 and 2017, respectively. The tax provision recorded in discontinued operations related to discontinued Chaucer business for the nine months ended September 30, 2018 was comprised of a $0.2 million U.S. federal income tax benefit and a $6.8 million foreign income tax expense. For the nine months ended September 30, 2017, the tax provision recorded in discontinued operations was comprised of a $6.1 million U.S. federal income tax expense and a $16.5 million foreign income tax benefit.

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 2014.