Aon is a leading global professional services firm providing a broad range of risk, retirement, and health solutions underpinned by proprietary data and analytics. Management is leading a set of initiatives designed to strengthen Aon and unite the firm with one portfolio of capability enabled by proprietary data and analytics and one operating model to deliver additional insight, connectivity, and efficiency.
Depreciation of fixed assets primarily relates to software, leasehold improvements, furniture, fixtures and equipment, computer equipment, buildings, and automobiles. Depreciation of fixed assets increased $25 million in 2017, or 15%, compared to 2016. The increase was primarily driven by $26 million of restructuring costs and a $14 million increase in expenses associated with acquisitions, net of divestitures, partially offset by $1 million of savings related to restructuring and other operational improvement initiatives as well as a decrease as we continue to optimize our real estate and information technology portfolio.
Short-term investments decreased $357 million at December 31, 2018 as compared to December 31, 2017. As disclosed in Note 16 “Fair Value Measurements and Financial Instruments” of the Financial Statements contained in Part II, Item 8 of this report, the majority of our investments carried at fair value are money market funds. These money market funds are held throughout the world with various financial institutions. We are not aware of any market liquidity issues that would materially impact the fair value of these investments.
Apart from commitments, guarantees, and contingencies, as disclosed herein and Note 17 “Claims, Lawsuits, and Other Contingencies” of the Notes to Consolidated Financial Statements in Part II, Item 8 of this report, the Company had no off-balance sheet arrangements that have, or are reasonably likely to have, a current or future material effect on the Company’s financial condition, results of operations, or liquidity. Our cash flows from operations, borrowing availability, and overall liquidity are subject to risks and uncertainties. See “Information Concerning Forward-Looking Statements” below.
The service cost component of net periodic benefit cost is reported in Compensation and benefits and all other components are reported in Other income (expense). We used a full-yield curve approach in the estimation of the service and interest cost
Holding all other assumptions constant, the following table reflects what a 25 basis point (“bps”) increase and decrease in our estimated discount rate would have on our projected benefit obligation at December 31, 2018 (in millions):
Holding all other assumptions constant, the following table reflects what a 25 bps increase and decrease in our discount rate would have on our estimated 2019 pension expense (in millions):
The Company previously recognized revenue either at a point in time or over a period of time based on the transfer of value to customers or as the remuneration became determinable. Under ASC 606, the revenue related to certain brokerage services recognized over a period of time is recognized on the effective date of the associated policies when control of the policy transfers to the customer. As a result, revenue from these arrangements are typically recognized in earlier periods under ASC 606 in comparison to ASC 605, changing the timing and amount of revenue recognized for annual and interim periods. This change resulted in a significant shift in timing of interim revenue for the Reinsurance Solutions revenue line and, to a lesser extent, certain other brokerage services.
As of December 31, 2018, Aon plc had two primary committed credit facilities outstanding: its $900 million multi-currency U.S. credit facility expiring in February 2021 (the “2021 Facility”) and its $400 million multi-currency U.S. credit facility expiring in October 2022 (the “2022 Facility”). On February 2, 2019, the Company extended the 2021 Facility by one year, and it will now expire in February 2022.
The Company leases office facilities, equipment, and automobiles under non-cancelable operating leases. These leases expire at various dates, may contain renewal and expansion options, and do not contain restrictions concerning dividends or incurring additional debt. In addition to base rental costs, occupancy lease agreements generally provide for rent escalations resulting from increased assessments for real estate taxes and other charges. The total amount of the minimum rent is expensed on a straight-line basis over the lease term. The Company’s lease obligations are primarily for the use of office space and certain real-estate properties are subleased to third parties.
For the tax impact of discontinued operations, see Note 5 “Discontinued Operations”.
Valuation allowances have been established primarily with regard to the tax benefits of certain net operating loss and capital loss carryforwards. Valuation allowances increased by $35 million as of December 31, 2018, when compared to December 31, 2017. The change is primarily attributable to capital loss carryforwards generated by the 2018 tax loss on disposition for which utilization is subject to limitation.
The Company recognizes interest and penalties related to uncertain tax positions in its provision for income taxes. The Company accrued potential interest and penalties of $22 million, $11 million, and $15 million in 2018, 2017, and 2016, respectively. The Company recorded a liability for interest and penalties of $77 million, $55 million, and $48 million as of December 31, 2018, 2017, and 2016, respectively.
Amounts recognized in Accumulated other comprehensive loss (income) that have not yet been recognized as components of net periodic benefit cost at December 31, 2018 and 2017 consist of (in millions):