Notes to Consolidated Financial Statements – (continued)
(Amounts in Millions, Except Per Share Amounts)
Gross unrealized and realized gains and losses for our long-term investments and short-term marketable securities were not material for the years ended December 31, 2015, 2014 and 2013.
Financial Instruments that are not Measured at Fair Value on a Recurring Basis
The following table presents information about our financial instruments that are not measured at fair value on a recurring basis as of December 31, 2015, and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value.
December 31, 2015
Total long-term debt
Our long-term debt is comprised of senior notes and other notes payable. The fair value of our senior notes traded over-the-counter is based on quoted prices for such securities, but for which fair value can also be derived from inputs that are readily observable. Therefore, these senior notes are classified as Level 2 within the fair value hierarchy. Our other notes payable are not actively traded, and their fair value is not solely derived from readily observable inputs. The fair value of our other notes payable is determined based on a discounted cash flow model and other proprietary valuation methods, and therefore is classified as Level 3 within the fair value hierarchy. See Note 2 for further information on our long-term debt.
Non-financial Instruments that are Measured at Fair Value on a Recurring Basis
Certain non-financial instruments are measured at fair value on a recurring basis, primarily accrued restructuring charges. Accrued restructuring charges were $3.9 and $8.1 for the years ended December 31, 2015 and 2014, respectively. These charges were valued using our internal estimates based upon a discounted cash flow model and are classified as Level 3 in the fair value hierarchy.
Non-financial Instruments that are Measured at Fair Value on a Nonrecurring Basis
Certain non-financial instruments are measured at fair value on a nonrecurring basis, primarily goodwill, intangible assets, and property and equipment. Accordingly, these assets are not measured and adjusted to fair value on an ongoing basis but are subject to periodic evaluations for potential impairment.
Note 12: Employee Benefits
Pension and Postretirement Benefit Plans
We have a defined benefit pension plan covering certain U.S. employees (the “Domestic Pension Plan”) that consists of approximately 3,700 participants and is closed to new participants. We also have numerous funded and unfunded plans outside the U.S. The Interpublic Limited Pension Plan in the U.K. is a defined benefit plan and is our most material foreign pension plan in terms of the benefit obligation and plan assets. Some of our domestic and foreign subsidiaries provide postretirement health benefits and life insurance to eligible employees and, in certain cases, their dependents. The domestic postretirement benefit plan is our most material postretirement benefit plan in terms of the benefit obligation. This plan consists of approximately 1,900 participants, is closed to new participants and is unfunded.
Differences between the aggregate income statement and balance sheet amounts listed in the tables below and the totals reported in our Consolidated Statements of Operations, Consolidated Statements of Comprehensive Income and Consolidated Balance Sheets relate to non-material foreign pension and postretirement benefit plans.