wijmo.angular2.grid.detail is an external TypeScript module that can be imported to your code using its ambient module name. For example:

import * as wjDetail from 'wijmo/wijmo.angular2.grid.detail';
import * as wjGrid from 'wijmo/wijmo.angular2.grid';
 
@Component({
    directives: [wjGrid.WjFlexGrid, wjDetail.WjFlexGridDetail],
    template: `
      <wj-flex-grid [itemsSource]="data">
          <ng-template wjFlexGridDetail>
              Detail row content here...
          </ng-template>
      </wj-flex-grid>`,
    selector: 'my-cmp',
})
export class MyCmp {
    data: any[];
}