Creating content type by setting parent content type id , Programatically using JSOM

Hi I am getting error that "Input string is not in correct format" when I am trying to create a content type programmatically by passing name, group, description & parent content type using property set_parentContentType('Document');

here set_name(), set_group(), set_description() are working fine & I am using JSOM model for development.

Please help me with this regard

DvG