The carrying value of our cash and cash equivalents, accounts receivable and accounts payable approximate fair value because of their short-term nature.

Our investments consist of U.S. Treasury notes with maturities of up to 16 months, with $343,616 maturing within one year from December 31, 2020. Fair value of investments is measured using Level 1 inputs (quoted prices for identical assets in active markets). We designate the appropriate classification of our investments at the time of purchase based upon the intended holding period.

Investments, all of which are classified as held-to-maturity, are carried at amortized cost. The fair value of these investments was less than the amortized cost by $117 as of December 31, 2020. We recognize a reserve for expected credit losses when lifetime credit losses are expected by management. As of December 31, 2020, management has concluded that there is no risk of non-payment. No impairment charges were recognized on our investments for the year ended December 31, 2020 and 2019.

We have elected to fund certain deferred compensation obligations through a rabbi trust, the assets of which are designated as trading securities, as described further in Note 9. “Employee Benefit Plans.”

Assets recognized or disclosed at fair value on the consolidated financial statements on a nonrecurring basis include items such as leasehold improvements, property and equipment, operating lease assets, other assets and goodwill. Fair value of these assets are measured using Level 3 inputs (unobservable inputs for the asset or liability). Unobservable inputs include the discount rate, projected restaurant revenues and expenses, and sublease income if we are closing the restaurant. These assets are measured at fair value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Carrying value after impairment approximates fair value.

The following table summarizes our assets measured at fair value by hierarchy level on a nonrecurring basis:



		Carrying Value
		December 31,
	Level	2020		2019
Leasehold improvements, property and equipment, net	3	$	4,682	$	1,411
Operating lease assets	3		10,372		4,270
Total		$	15,054	$	5,681

For the years ended December 31, 2020, 2019 and 2018 we recorded asset impairments related to restaurants and offices of $16,683, $2,897 and $56,093 respectively.

On April 16, 2020, we acquired approximately 10% of the common stock of a supplier in exchange for cash consideration of $7,500. On August 6, 2020, we acquired an additional 3.2% of the common stock of a supplier in exchange for cash consideration of $2,500. As of December 31, 2020, we own approximately 12.9% of the supplier’s common stock and have invested total cash