In the Quartus® II Pin Planner view you will see the current strength will have the default settings if you have not explicitly set current strength assignments in your design.
For example, in a Cyclone® IV GX device using a 2.5V (default) I/O standard, you will see a drive strength of 16mA(default). This however is not the actual default current strength. You need to refer to compilation report for the actual current strength. For Cyclone IV GX devices, the default current strength setting is 50ohm OCT without calibration for all non-voltage reference and HSTL/SSTL Class I I/O standards and 25ohm OCT without calibration for HSTL/SSTL Class II I/O standards.
Refer to the respective device handbook for the default I/O setting, it will either be a current strength setting or a non-calibrated OCT setting.