Consulting operating income increased $80 million or 8% to $1.1 billion in 2015 compared with 2014, reflecting flat revenue, but an increase of 5% on an underlying basis. Expense decreased 1%, but increased 4% on an underlying basis. Mercer and Oliver Wyman recorded underlying revenue growth of 4% and 7%, respectively, in 2015 as compared to 2014. The operating income and revenue in 2015 include a pre-tax gain of $37 million from the sale of Mercer's U.S. defined contribution recordkeeping business.
Consolidated operating expenses increased 5% in 2014 compared with the same period in 2013 and 4% on an underlying basis. The increase in underlying expenses primarily reflects higher incentive compensation, facilities and software amortization costs, partly offset by lower pension costs.
The Company is organized as a holding company, a legal entity separate and distinct from its operating subsidiaries. As a holding company without significant operations of its own, the Company is dependent upon dividends and other payments from its operating subsidiaries to meet its obligations for paying principal and interest on outstanding debt obligations, for paying dividends to stockholders, for share repurchases and for corporate expenses. We also provide financial support to our operating subsidiaries for acquisitions, investments and certain parts of their business that require liquidity, such as the capital markets raising business of Guy Carpenter. Other sources of liquidity include borrowing facilities discussed below in financing cash flows.
In September 2015, the Company issued $600 million of 3.75% 10.5-year senior notes. The Company used the net proceeds for general corporate purposes.
In March 2015, the Company issued $500 million of 2.35% five-year senior notes. The Company used the net proceeds for general corporate purposes.
During 2014, the Risk and Insurance Services segment completed the following fifteen acquisitions:
January - MMA acquired Barney & Barney, LLC, a San Diego-based insurance broking firm that provides insurance, risk management and employee benefits solutions to businesses and individuals throughout the U.S. and abroad, Great Lakes Employee Benefits Services, Inc., an employee group benefits consulting and brokerage firm based in Michigan, and Bond Network, Inc., a surety bonding agency based in North Carolina.
The projected benefit obligation and fair value of plan assets for non-U.S. pension plans with projected benefit obligations in excess of plan assets was $1.9 billion and $1.5 billion, respectively, as of December 31, 2015 and $2.2 billion and $1.6 billion, respectively, as of December 31, 2014.
The Company has categorized its assets and liabilities that are valued at fair value on a recurring basis into a three-level fair value hierarchy as defined by the accounting literature. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets and liabilities (Level 1) and lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy, for disclosure purposes, is determined based on the lowest level input that is significant to the fair value measurement. Assets and liabilities recorded in the consolidated balance sheets at fair value are categorized based on the inputs in the valuation techniques as follows:
The Company's investments in private equity funds were $76 million and $61 million at December 31, 2015 and December 31, 2014, respectively. The carrying values of these private equity investments approximates fair value. The underlying private equity funds follow investment company accounting, where investments within the fund are carried at fair value. The Company records in earnings, investment gains/losses for its proportionate share of the change in fair value of the funds. These investments would be classified as Level 3 in the fair value hierarchy and are included in other assets in the consolidated balance sheets.