The Company's credit facility exposes the Company to risks associated with the variability in interest expense associated with fluctuations in LIBOR. To partially mitigate this risk, the Company entered into interest rate swaps. As of September 26, 2021, the Company had a combined notional principal amount of $200 million of interest rate swap agreements, all of which are designated as cash flow hedges. These swap agreements effectively convert the interest expense associated with a portion of the Company's variable rate debt from variable interest rates to fixed interest rates and have maturities ranging from February 2022 to March 2022.

The following table summarizes the fair value of derivative contracts included in the condensed consolidated balance sheets (in thousands):


	Fair value of derivative instruments
Derivatives accounted for as cash flow hedges	Balance sheet location	September 26, 2021		December 31, 2020
Interest rate swaps	Accrued liabilities	$	2,506	$	—
Interest rate swaps	Other long-term liabilities	$	—	$	6,567

The interest rate swaps are comprised of over-the-counter derivatives, which are valued using models that primarily rely on observable inputs such as yield curves and are classified as Level 2 in the fair value hierarchy.