(4)   Assets and Liabilities Measured at Fair Value

For assets and liabilities required to be reported at fair value, GAAP provides a hierarchy that prioritizes inputs to valuation techniques used to measure fair value into three broad levels. Level 1 inputs are quoted market prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2 inputs are inputs, other than quoted market prices included within Level 1, that are observable for the asset or liability, either directly or indirectly. Level 3 inputs are unobservable inputs for the asset or liability.

The Company's assets and liabilities measured at fair value are as follows:

​

​

The majority of the Company's Level 2 financial assets and liabilities are primarily debt instruments and derivative instruments with quoted market prices that are not considered to be traded on "active markets," as defined in GAAP. The fair values for such instruments are derived from a typical model using observable market data as the significant inputs.

​

Realized and Unrealized Gains (Losses) on Financial Instruments

Realized and unrealized gains (losses) on financial instruments are comprised of changes in the fair value of the following:

​

​

The Company has elected to account for its exchangeable debt using the fair value option. Changes in the fair value of the exchangeable senior debentures recognized in the condensed consolidated statement of operations are primarily due to market factors primarily driven by changes in the fair value of the underlying shares into which the debt is exchangeable. The Company isolates the portion of the unrealized gain (loss) attributable to the change in the instrument specific credit risk and recognizes such amount in other comprehensive earnings (loss).  During the three months ended March 31, 2023, the Company recognized $25 million of previously unrecognized gains, which was recognized through realized and unrealized gains (losses) on financial instruments, net on the condensed consolidated statement of operations. The change in the fair value of the exchangeable senior debentures attributable to changes in the instrument specific credit risk was a loss of $129 million and a gain of $169 million for the three months ended March 31, 2024 and 2023, respectively.  The cumulative change was a gain of $410 million as of March 31, 2024, net of the recognition of previously unrecognized gains and losses.