overstaying in china with expired passport

hi this is marian , filipino. I overstayed here in china for two years and i am ready to go to shanghai soon to surrender myself in the nearest PSB... I want to know if i pay the penalty 10000 rmb , should they still put me in detention ? how about if my passport was expired, can i buy my plane ticket or should i go to philippine consulate first to apply for travel document? thanks. i need your advice