The following table presents the credit quality of amounts due from reinsurers as of December 31, 2020. Amounts due from reinsurers are net of reserves for uncollectible reinsurance of $1 million in the aggregate. (In thousands) Reinsurer Rating (1) Amount Amounts due in excess of $20 million: Munich Re AA- $ 275,841  Lloyd’s of London A+ 255,184  Swiss Re AA- 182,532  Alleghany Group A+ 182,015  Partner Re A+ 164,535  Hannover Re Group AA- 129,752  Berkshire Hathaway AA+ 104,775  Everest Re A+ 102,085  Renaissance Re A+ 101,014  Axis Capital A+ 87,948  Liberty Mutual A 66,263  Korean Re A 56,091  Fairfax Financial A- 37,310  Axa Insurance AA- 35,012  Validus Holdings Ltd. A 29,599  Arch Capital Group A+ 27,739  Qatar Re A 20,321  Other reinsurers: Rated A- or better 178,473  Secured (2) 122,573  All Others 29,883  Subtotal $ 2,188,945  Residual market pools (3) 243,358  Allowance for expected credit losses (7,801) Total $ 2,424,502  (1) S&P rating, or if not rated by S&P, A.M. Best rating. (2) Secured by letters of credit or other forms of collateral. (3) Many states require licensed insurers that provide workers' compensation insurance to participate in programs that provide workers' compensation to employers that cannot procure coverage from an insurer on a voluntary basis. Insurers can fulfill this residual market obligation by participating in pools where results are shared by the participating companies. The Company acts as a servicing carrier for workers' compensation pools in certain states. As a servicing carrier, the Company writes residual market business directly and then cedes 100% of this business to the respective pool. As a servicing carrier, the Company receives fee income for its services. The Company does not retain underwriting risk, and credit risk is limited as ceded balances are jointly shared by all the pool members. 52