Obama's overarching "ideology" continues to be Anti-Stupid. In foreign policy this sometimes looks like Realism, but he's not actually opposed to doing the right thing when we have no clear interests. Instead, he's opposed to trying to do the right thing when the effort would be stupid.
Jonathan Chait What Is Obama's Foreign Policy Ideology?:
Big-R Realists dismiss the role of values in foreign policymaking, believing that states ought to (and almost always do) follow their interests, even if they delude themselves or others that they have some grander moral purpose, like human rights or democracy. The ultimate modern expression of Realism would be Richard Nixon and Henry Kissinger, who tolerated a bloodbath by Cold War ally Pakistan, and who once took the Realist philosophy to its reduction ne plus ultra by commenting privately, “And if they put Jews into gas chambers in the Soviet Union, it is not an American concern.” The ultimate expression of the opposite of Realism, idealism, might be post-9/11 George W. Bush, declaring war on evil everywhere, pledging “the ultimate goal of ending tyranny in our world.”
The reason Obama has had liberal humanitarians like Power and Susan Rice on his foreign policy staff since has campaign, and throughout his presidency, is that he shares their ideological goals within the limits of what is practically attainable. Obviously, Obama is no George W. Bush. On the other hand, nobody else is George W. Bush, either. Most American presidents fall somewhere on the continuum between Bushian crusading moralism and Nixonian ruthlessness. Obama does, too.