Net Assets Investment Company, Portfolio Turnover C000158412 [Member] American Funds Retirement Income Portfolio — Conservative - Class A C000158417 [Member] American Funds Retirement Income Portfolio — Conservative - Class C C000189476 [Member] American Funds Retirement Income Portfolio — Conservative - Class T C000158418 [Member] American Funds Retirement Income Portfolio — Conservative - Class F-1 C000158433 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-4 C000164837 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-5E C000158434 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-5 C000158435 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-6 C000189477 [Member] American Funds Retirement Income Portfolio — Enhanced - Class T C000158427 [Member] American Funds Retirement Income Portfolio — Enhanced - Class F-1 C000158428 [Member] American Funds Retirement Income Portfolio — Enhanced - Class F-2 C000180021 [Member] American Funds Retirement Income Portfolio — Enhanced - Class F-3 C000158429 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-1 C000158430 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-2 C000158431 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-2E C000158432 [Member] American Funds Retirement Income Portfolio — Enhanced - Class R-3 C000158436 [Member] American Funds Retirement Income Portfolio — Moderate - Class A C000158438 [Member] American Funds Retirement Income Portfolio — Moderate - Class C C000189478 [Member] American Funds Retirement Income Portfolio — Moderate - Class T C000158439 [Member] American Funds Retirement Income Portfolio — Moderate - Class F-1 C000158440 [Member] American Funds Retirement Income Portfolio — Moderate - Class F-2 C000180022 [Member] American Funds Retirement Income Portfolio — Moderate - Class F-3 C000158441 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-1 C000158442 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-2 C000158443 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-2E C000158444 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-3 C000158445 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-4 C000164838 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-5E C000158446 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-5 C000158447 [Member] American Funds Retirement Income Portfolio — Moderate - Class R-6 C000158424 [Member] American Funds Retirement Income Portfolio — Enhanced - Class A C000158426 [Member] American Funds Retirement Income Portfolio — Enhanced - Class C C000158419 [Member] American Funds Retirement Income Portfolio — Conservative - Class F-2 C000180020 [Member] American Funds Retirement Income Portfolio — Conservative - Class F-3 C000158420 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-1 C000158421 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-2 C000158422 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-2E C000158423 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-3 C000158413 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-4 C000164836 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-5E C000158414 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-5 C000158415 [Member] American Funds Retirement Income Portfolio — Conservative - Class R-6 Investment Type [Axis] Equity-income funds [Member] Balanced funds [Member] Fixed income funds [Member] Other assets less liabilities [Member] Growth-and-income funds [Member] Growth funds [Member]