12. SEGMENT REPORTING The U.S. Reinsurance operation writes property and casualty reinsurance and specialty lines of business, including Marine, Aviation, Surety and Accident and Health ("A&amp;H") business, on both a treaty and facultative basis, through reinsurance brokers, as well as directly with ceding companies primarily within the U.S. The International operation writes non-U.S. property and casualty reinsurance through Everest Re's branches in Canada, Singapore and through offices in Brazil, Miami and New Jersey. The Insurance operation writes property and casualty insurance directly and through brokers, surplus lines brokers and general agents mainly within the U.S. These segments are managed independently, but conform with corporate guidelines with respect to pricing, risk management, control of aggregate catastrophe exposures, capital, investments and support operations. Management generally monitors and evaluates the financial performance of these operating segments based upon their underwriting results. Underwriting results include earned premium less losses and LAE incurred, commission and brokerage expenses and other underwriting expenses. We measure our underwriting results using ratios, in particular loss, commission and brokerage and other underwriting expense ratios, which, respectively, divide incurred losses, commissions and brokerage and other underwriting expenses by premiums earned. The Company does not maintain separate balance sheet data for its operating segments. Accordingly, the Company does not review and evaluate the financial results of its operating segments based upon balance sheet data. The following tables present the underwriting results for the operating segments for the periods indicated: Three Months Ended Six Months Ended U.S. Reinsurance June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 641,763 $ 652,110 $ 1,405,903 $ 1,296,332 Net written premiums 487,694 429,931 1,105,835 853,762 Premiums earned $ 605,136 $ 467,509 $ 1,180,040 $ 908,894 Incurred losses and LAE 367,473 708,524 684,111 1,009,728 Commission and brokerage 172,589 148,711 339,692 276,031 Other underwriting expenses 15,728 15,472 31,319 32,358 Underwriting gain (loss) $ 49,346 $ (405,198 ) $ 124,918 $ (409,223 ) Three Months Ended Six Months Ended International June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 372,671 $ 398,714 $ 761,642 $ 765,738 Net written premiums 350,219 337,357 708,077 672,232 Premiums earned $ 353,086 $ 343,133 $ 675,460 $ 672,072 Incurred losses and LAE 213,808 259,487 450,884 435,846 Commission and brokerage 85,974 84,379 155,836 162,773 Other underwriting expenses 9,632 9,869 18,097 19,955 Underwriting gain (loss) $ 43,672 $ (10,602 ) $ 50,643 $ 53,498 Three Months Ended Six Months Ended Insurance June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 673,603 $ 581,460 $ 1,205,374 $ 1,036,445 Net written premiums 481,952 423,066 898,196 771,387 Premiums earned $ 417,401 $ 369,194 $ 790,577 $ 714,880 Incurred losses and LAE 261,941 260,749 504,323 496,441 Commission and brokerage 58,212 54,912 109,465 105,655 Other underwriting expenses 57,991 48,885 112,317 99,264 Underwriting gain (loss) $ 39,257 $ 4,648 $ 64,472 $ 13,520 The following table reconciles the underwriting results for the operating segments to income (loss) before taxes as reported in the consolidated statements of operations and comprehensive income (loss) for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Underwriting gain (loss) $ 132,275 $ (411,152 ) $ 240,033 $ (342,205 ) Net investment income 90,709 72,070 175,243 141,979 Net realized capital gains (losses) 142,563 (42,271 ) 277,619 (102,472 ) Corporate expense (2,519 ) (1,513 ) (4,170 ) (5,109 ) Interest, fee and bond issue cost amortization expense (9,684 ) (7,623 ) (19,512 ) (14,936 ) Other income (expense) (3,812 ) 77,682 (5,026 ) 2,805 Income (loss) before taxes $ 349,532 $ (312,807 ) $ 664,187 $ (319,938 ) The Company produces business in the U.S. and internationally. The net income deriving from assets residing in the individual foreign countries in which the Company writes business are not identifiable in the Company's financial records. Based on gross written premium, the table below presents the largest country, other than the U.S., in which the Company writes business, for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Canada gross written premiums $ 47,206 $ 44,189 $ 86,256 $ 84,581 No other country represented more than 5 % of the Company's revenues.