15. 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 Res branches in Canada and Singapore and through offices in Brazil, Miami and New Jersey. The Bermuda operation provides reinsurance and insurance to worldwide property and casualty markets through brokers and directly with ceding companies from its Bermuda office and reinsurance to the United Kingdom and European markets through its UK branch and Ireland Re. The Insurance operation writes property and casualty insurance directly and through brokers, surplus lines brokers and general agents within the U.S., Canada and Europe. 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 loss adjustment expenses (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. For inter-affiliate reinsurance and business written through the Lloyds Syndicate, business is generally reported within the segment in which the business was first produced, consistent with how the business is managed. 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 $ 641,764 $ 652,109 $ 1,405,910 $ 1,296,331 Net written premiums 506,840 566,303 1,176,547 1,112,134 Premiums earned $ 620,780 $ 603,884 $ 1,247,251 $ 1,167,269 Incurred losses and LAE 351,725 509,653 671,829 1,054,846 Commission and brokerage 172,602 148,712 339,704 276,032 Other underwriting expenses 15,727 15,472 31,318 32,358 Underwriting gain (loss) $ 80,726 $ ( 69,953) $ 204,400 $ ( 195,967) Three Months Ended Six Months Ended International June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 372,861 $ 399,024 $ 772,915 $ 765,748 Net written premiums 357,917 355,309 733,422 700,464 Premiums earned $ 360,075 $ 363,795 $ 711,010 $ 707,399 Incurred losses and LAE 212,972 301,406 467,107 428,430 Commission and brokerage 88,170 92,088 169,595 174,265 Other underwriting expenses 9,835 10,349 18,516 20,925 Underwriting gain (loss) $ 49,098 $ ( 40,048) $ 55,792 $ 83,779 Three Months Ended Six Months Ended Bermuda June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 394,962 $ 369,440 $ 762,813 $ 785,126 Net written premiums 369,929 355,236 719,270 750,204 Premiums earned $ 362,905 $ 353,698 $ 693,018 $ 672,832 Incurred losses and LAE 218,385 250,097 416,344 379,610 Commission and brokerage 84,606 80,318 158,716 161,805 Other underwriting expenses 11,868 10,762 23,365 20,895 Underwriting gain (loss) $ 48,046 $ 12,521 $ 94,593 $ 110,522 Three Months Ended Six Months Ended Insurance June 30, June 30, (Dollars in thousands) 2019 2018 2019 2018 Gross written premiums $ 757,068 $ 645,948 $ 1,352,125 $ 1,150,923 Net written premiums 549,297 469,530 1,006,442 855,782 Premiums earned $ 473,539 $ 408,441 $ 898,717 $ 801,745 Incurred losses and LAE 311,548 280,158 587,900 535,605 Commission and brokerage 75,572 62,284 142,409 128,939 Other underwriting expenses 67,403 56,516 130,619 115,205 Underwriting gain (loss) $ 19,016 $ 9,483 $ 37,789 $ 21,996 The following table reconciles the underwriting results for the operating segments to income 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) $ 196,886 $ ( 87,997) $ 392,574 $ 20,330 Net investment income 179,028 141,322 320,004 279,616 Net realized capital gains (losses) 30,272 15,776 122,504 ( 9,125) Net derivative gain (loss) 353 2,987 3,584 3,260 Corporate expenses ( 7,535) ( 6,633) ( 14,187) ( 15,629) Interest, fee and bond issue cost amortization expense ( 8,434) ( 7,728) ( 16,065) ( 15,146) Other income (expense) ( 7,977) 3,036 ( 17,030) 15,100 Income (loss) before taxes $ 382,593 $ 60,763 $ 791,384 $ 278,406 The Company produces business in the U.S., Bermuda and internationally. The net income deriving from and assets residing in the individual foreign countries in which the Company writes business are not identifiable in the Companys 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 United Kingdom gross written premium $ 207,140 $ 177,072 $ 470,997 $ 435,331 No other country represented more than 5% of the Companys revenues.