As discussed in Note 10 to these consolidated financial statements, on May 16, 2017, our stockholders approved the LTIP, which replaced our previous stockholder-approved 2014 LTIP. The LTIP provides for the grant of a stock award either as restricted stock or as restricted stock units to officers, employees and non-employee directors. In either case, the compensation committee may determine that the award will be subject to the attainment of performance measures over an established performance period. Stock awards and the related dividend equivalents are non-transferable and subject to forfeiture if the holder does not remain continuously employed with us during the applicable restriction period or, in the case of a performance-based award, if applicable performance measures are not attained. The compensation committee will determine all of the terms relating to the satisfaction of performance measures and the termination of a restriction period, or the forfeiture and cancellation of a restricted stock award upon a termination of employment, whether by reason of disability, retirement, death or any other reason.

The agreements awarding restricted stock units under the LTIP will specify whether such awards may be settled in shares of our common stock, cash or a combination of shares and cash and whether the holder will be entitled to receive dividend equivalents, on a current or deferred basis, with respect to such award. Prior to the settlement of a restricted stock unit, the holder of a restricted stock unit will have no rights as a stockholder of the company. The maximum number of shares available under the LTIP for restricted stock, restricted stock units and performance unit awards settled with stock (i.e., all awards other than stock options and stock appreciation rights) is 4.0 million. At December 31, 2020, 2.3 million shares were available for grant under the LTIP for such awards.

In 2020, 2019 and 2018, we granted 422,610, 414,700 and 439,100 restricted stock units, respectively, to employees under the LTIP and 2014 LTIP, with an aggregate fair value of $34.9 million, $31.8 million and $28.7 million, respectively, at the date of grant.

The 2020, 2019 and 2018 restricted stock units vest as follows: 405,870 units granted in first quarter 2020, 399,900 units granted in first quarter 2019 and 420,200 units granted in first quarter 2018 vest in full based on continued employment through March 12, 2025, March 14, 2024 and March 15, 2023, respectively, while the other 2020, 2019 and 2018 restricted stock unit awards generally vest in full based on continued employment through the vesting period on the anniversary date of the grant. For certain of our executive officers age 55 or older, restricted stock units awarded in 2020, 2019 and 2018 are not subject to forfeiture upon such officers’ departure from the company after two years from the date of grant.

The vesting periods of the 2020, 2019 and 2018 restricted stock unit awards are as follows (in actual shares):

	Restricted Stock Units Granted
Vesting Period	2020		2019		2018
One year		16,740		14,800		18,900
Two years		8,870		12,000		12,700
Five years		397,000		387,900		407,500
Total shares granted		422,610		414,700		439,100

We account for restricted stock awards at historical cost, which equals its fair market value at the date of grant, which is amortized to compensation expense ratably over the vesting period of the participants. Future changes in the fair value of our common stock that is owed to the participants do not have any impact on the amounts recorded in our consolidated financial statements. During 2020, 2019 and 2018, we charged $40.0 million, $29.8 million and $27.2 million, respectively, to compensation expense related to restricted stock awards granted in 2009 through 2020. The total intrinsic value of unvested restricted stock at December 31, 2020 and 2019 was $302.4 million and $215.1 million, respectively. During 2020 and 2019, equity awards (including accrued dividends) with an aggregate fair value of $2.0 million and $2.1 million were vested and distributed to employees under this plan.

On March 12, 2020, March 14, 2019 and March 15, 2018, pursuant to the LTIP, the compensation committee approved 82,500, 73,600 and 78,200, respectively of provisional performance share awards, with an aggregate fair value of $7.1 million, $5.8 million and $5.3 million, respectively, for future grants to our officers and key employees. Each performance unit award was equivalent to the value of one share of our common stock on the date such provisional award was approved. At the end of the performance period, eligible participants will receive a number of earned shares based on the growth in adjusted EBITDAC per share (as defined in the 2020 Proxy Statement). Earned shares for the 2020, 2019 and 2018 provisional awards will fully vest based on continuous employment through March 12, 2023, March 14, 2022 and March 15, 2021, respectively, and will be settled in unrestricted shares of our common stock on a one-for-one basis as soon as practicable in 2023, 2022 and 2021, respectively. The 2020, 2019 and 2018 awards are subject to a three-year performance period that begins on January 1, 2020, 2019 and 2018, respectively, and vest on the three-year anniversary of the date of grant (March 12, 2023, March 14, 2022 and March 15, 2021). For certain of our executive officers age 55 or older, awards granted in 2020, 2019 and 2018 are no longer subject to forfeiture upon such officers’ departure from the company after two years from the date of grant. During 2020, 2019 and 2018, equity awards (including accrued dividends) with an aggregate fair value of $12.5 million, $5.7 million and $3.7 million was vested and distributed to employees under this plan.

On March 12, 2020, pursuant to our Performance Unit Program (which we refer to as the Program), the compensation committee approved provisional cash awards of $18.4 million in the aggregate for future grants to our officers and key employees that are denominated in units (213,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. The Program consists of a one-year performance period based on our financial performance and a three-year vesting period measured from January 1 of the year of grant. At the discretion of the compensation committee and determined based on our performance, the eligible officer or key employee will be granted a percentage of the provisional cash award units that equates to the EBITDAC growth achieved (as defined in the Program). At the end of the performance period, eligible participants will be granted a number of units based on achievement of the performance goal and subject to approval by the compensation committee. Granted units for the 2020 provisional award will fully vest based on continuous employment through January 1, 2023. The ultimate award value will be equal to the trailing twelve-month price of our common stock on December 31, 2022, multiplied by the number of units subject to the award, but limited to between 0.5 and 1.5 times the original value of the units determined as of the grant date. The fair value of the awarded units will be paid out in cash as soon as practicable in 2023. If an eligible employee leaves us prior to the vesting date, the entire award will be forfeited. We did not recognize any compensation expense during the year ended December 31, 2020 related to the 2020 provisional award under the Program. Based on company performance for 2020, we expect to grant 209,000 units under the Program in first quarter 2021 that will fully vest on January 1, 2023.

On March 14, 2019, pursuant to the Program, the compensation committee approved provisional cash awards of $16.5 million in the aggregate for future grants to our officers and key employees that are denominated in units (206,800 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2019 provisional award were similar to the terms of the 2020 provisional awards. Based on our performance for 2019, we granted 200,000 units under the Program in first quarter 2020 that will fully vest on January 1, 2022. During 2020, we charged $10.6 million to compensation expense related to these awards. We did not recognize any compensation expense during 2019 related to the 2019 provisional award under the Program.

On March 15, 2018, pursuant to the Program, the compensation committee approved provisional cash awards of $15.0 million in the aggregate for future grants to our officers and key employees that are denominated in units (219,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2018 provisional award were similar to the terms of the 2019 provisional awards. Based on our performance for 2018, we granted 190,000 units under the Program in first quarter 2019 that fully vested on January 1, 2021. During 2020 and 2019, we charged $9.9 million and $8.9 million to compensation expense related to these awards. We did not recognize any compensation expense during 2018 related to the 2018 provisional award under the Program.

On March 16, 2017, pursuant to the Program, the compensation committee approved provisional cash awards of $14.3 million in the aggregate for future grants to our officers and key employees that are denominated in units (255,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional awards were approved. Terms of the 2017 provisional award were similar to the terms of the 2018 provisional awards. Based on our performance for 2017, we granted 242,000 units under the Program in first quarter 2018 that fully vested on January 1, 2020. During 2019 and 2018, we charged $10.3 million and $8.7 million to compensation expense related to these awards, respectively.

On March 17, 2016, pursuant to the Program, the compensation committee approved provisional cash awards of $17.4 million in the aggregate for future grants to our officers and key employees that are denominated in units (397,000 units in the aggregate), each of which was equivalent to the value of one share of our common stock on the date the provisional award was approved. Terms of the 2016 provisional award were similar to the terms of the 2017 provisional awards. Based on our performance for 2016, we granted 385,000 units under the Program in first quarter 2017 that fully vested on January 1, 2019. During 2018, we charged $11.7 million to compensation expense related to these awards.

During 2019, cash awards related to the 2016 provisional awards with an aggregate fair value of $22.4 million (341,000 units in the aggregate) were vested and distributed to employees under the Program. During 2018, cash awards related to the 2015 provisional awards with an aggregate fair value of $15.8 million (269,000 units in the aggregate) were vested and distributed to employees under the Program. During 2017, cash awards related to the 2014 provisional awards with an aggregate fair value of $9.3 million (199,000 units in the aggregate) were vested and distributed to employees under the Program.