Restricted Stock Units The Company grants RSUs to certain employees and non-employee directors. The grants vest after a designated period of time, generally three years for employees and two years for non-employee directors. The following table shows changes in nonvested RSUs: RSU Awards 2021 Shares in thousands Shares Grant Date Fair Value 1 Nonvested at Jan 1, 2021 3,007 $ 53.78 Granted 1,715 $ 57.96 Vested (1,063) $ 60.86 Canceled (116) $ 54.17 Nonvested at Dec 31, 2021 3,543 $ 53.67 1. Weighted-average per share. Additional Information about RSUs In millions, except per share amounts 2021 2020 2019 Weighted-average fair value per share of RSUs granted $ 57.96 $ 47.66 $ 54.78 Total fair value of RSUs vested 1 $ 33 $ 106 $ 264 Related tax benefit $ 7 $ 24 $ 59 Total compensation expense for RSU awards $ 95 $ 93 $ 110 Related tax benefit $ 21 $ 21 $ 25 1. Includes the fair value of shares vested in prior years and delivered in the reporting year. In 2021 , the Company did not settle any RSU's in cash (approximately 85,000 RSUs settled in cash for $4 million in 2020 and 341,000 RSUs settled in cash for $19 million in 2019 ). Total unrecognized compensation cost related to RSU awards of $71 million at December 31, 2021 is expected to be recognized over a weighted-average period of 1.64 years. At December 31, 2021 , approximately 1.8 million RSUs with a grant date weighted-average fair value per share of $52.92 had previously vested, but were not issued. These shares are scheduled to be issued to employees within six months to three years or to non-employee directors upon retirement. Performance Stock Units The Company grants PSUs to certain employees. The grants vest when the Company attains specified performance targets, such as return on capital, cumulative cash from operations and relative total shareholder return, over a predetermined period, generally one year to three years . Performance and payouts are determined independently for each metric. Compensation expense related to PSU awards is recognized over the lesser of the service or performance period. Changes in the fair value of liability instruments are recognized as compensation expense each quarter. The following table shows the PSU awards granted: PSU Awards Target Shares Granted 1 Grant Date Fair Value 2 Shares in thousands Year Performance Period 2021 Jan 1, 2021 – Dec 31, 2023 1,223 $ 61.48 2020 Jan 1, 2020 – Dec 31, 2022 1,426 $ 48.35 2019 Apr 1, 2019 – Dec 31, 2021 1,173 $ 57.58 1. At the end of the performance period, the actual number of shares issued can range from zero to 200 percent of target shares granted for the 2019 and 2021 awards and can range from zero to 100 percent of the target shares granted for the 2020 award. 2. Weighted-average per share. 138