German idealism
Neo-Kantianism refers broadly to a revived type of philosophy along the lines of that laid down by Immanuel Kant in the 18th century, or more specifically by Schopenhauer's criticism of the Kantian philosophy in his work "The World as Will and Representation" (1818), as well as by other post-Kantian philosophers such as Jakob Friedrich Fries and Johann Friedrich Herbart. It has some more specific reference in later German philosophy.
T. K. Seung
"Kant: A Guide for the Perplexed" (2007) provides an overview of Kant's philosophical development. This development has been understood as his struggle to reconcile continental rationalism and British empiricism, which has produced his a priori formalism. But this is only one half of the story, according to Seung; the other half is Kant's normative Platonism. In Kant's own language, Seung says, his philosophy consists of two types of elements: transcendent and transcendental. The transcendental elements are a priori and innate to the subject of experience. The transcendent elements transcend the world of experience. The former was Kant's appropriation of the Cartesian legacy; the latter was his adaptation of the Platonic legacy.