Fair value is a market-based measurement, not an entity-specific measurement. Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, the Company utilizes the U.S. GAAP fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumption about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy).

The inputs used to measure fair value are classified into the following fair value hierarchy:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Level 3 includes values determined using pricing models, discounted cash flow methodologies, or similar techniques reflecting the Company’s own assumptions.

In instances where the determination of the fair value hierarchy measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment of factors specific to the asset or liability. Transfers between levels within the fair value hierarchy are recognized by the Company on the date of the change in circumstances that requires such transfer. There were no transfers between levels during the six-month periods ended June 30, 2021 or 2020.

The following table sets forth, by level within the fair value hierarchy, the financial assets and liabilities recorded at fair value on a recurring basis as of June 30, 2021 and December 31, 2020 (in millions):

	June 30, 2021		Level 1		Level 2		Level 3
Investments in equity securities	$	127	$	127	$	—	$	—
Available-for-sale debt securities		138		—		138		—
Trading securities		12		—		12		—
Total assets	$	277	$	127	$	150	$	—

	December 31, 2020		Level 1		Level 2		Level 3
Investments in equity securities	$	129	$	129	$	—	$	—
Available-for-sale debt securities		110		—		110		—
Trading securities		12		—		12		—
Total assets	$	251	$	129	$	122	$	—

Investments in Equity Securities, Available-for-Sale Debt Securities and Trading Securities

Investments in equity securities and trading securities classified as Level 1 are measured using quoted market prices. Level 2 available-for-sale debt securities and trading securities primarily consisted of bonds and notes issued by the United States government and its agencies and domestic and foreign corporations. The estimated fair values of these securities are determined using various valuation techniques, including a multi-dimensional relational model that incorporates standard observable inputs and assumptions such as benchmark yields, reported trades, broker/dealer quotes, issuer spreads, benchmark securities, bids/offers and other pertinent reference data.