A travel document will help immigrants in the United States, to travel abroad from the United States and get back to the country and to obtain a travel document, you will have to file Form I-131. You may file this form to get a refugee travel document, a re-entry permit or an advance parole document. If a person who has filed Form I-485, Application to Adjust Status to Permanent Resident, wishes to travel abroad while his petition is pending, he may obtain an advance parole document and travel abroad. Similarly, a Green Card holder who wishes to travel abroad for more than one year, may do so by obtaining a re-entry permit. Refugee travel documents are meant for non US citizens who are granted refugee or asylee status in the country and they can obtain refugee travel documents and travel abroad.
A Green Card holder who looks forward to obtain a re-entry permit must file Form I-131, while in the country and he cannot file this form while in a foreign country. While filing this form to obtain a re-entry permit, you must appear for biometrics and the USCIS will deny your application if you miss your biometrics appointment. After that you can travel abroad and request the USCIS to mail your permit to a US Consulate abroad and you can collect this document from the overseas consulate. You can also choose to remain in the country and travel abroad after you receive your re-entry permit. USCIS takes around 6 months to process these applications and at times it processes the applications sooner. These re-entry permits are good only for a two year period and these permits cannot be renewed. However, a Green Card holder may apply for a new permit if the existing permit expires. But remember that you will not be issued a new permit, if the permit that you hold is still valid.
You may file Form I-131, to obtain an advance parole document while filing Form I-485. You will have to leave the country only after the USCIS approves your application and this document is valid for a one year period. Similarly, you cannot file Form I-131 to obtain a refugee travel document while abroad. However, you may depart after filing your application and after submitting your fingerprints and you can collect the document from an overseas consulate. This document is also valid for one year. You may renew an advance parole document and a refugee travel document but remember that re-entry permits cannot be renewed. The form i 131 filing fee may differ based on the application type. Check out the filing fee for form i131.