Politicians are asking questions and demanding answers. Sen. Frank Pallone Jr. (D-N.J.), ranking member of the Senate Energy and Commerce Committee, has requested information from six companies certified as IDR entities.

One of the key projects is an effort to strengthen the company's relationship with physicians.

"The combination of record account balances, strong savings behaviors and effective plan design tell an encouraging story about how Americans are approaching retirement," said Sharon Brovelli, president of workplace investing at Fidelity Investments.