DefinitelyTyped/types/next/document.d.ts

import * as React from 'react';

export interface DocumentProps {
    __NEXT_DATA__?: any;
    dev?: boolean;
    chunks?: string[];
    head?: Array<React.ReactElement<any>>;
    styles?: Array<React.ReactElement<any>>;
    [key: string]: any;
}

export class Head extends React.Component<any> {}
export class Main extends React.Component {}
export class NextScript extends React.Component {}
export default class extends React.Component<DocumentProps> {}