We measure all share-based payments to employees, including grants of stock options, and use a fair-value-based method for the recording of related compensation expense in our results of operations. In determining the expense we record for stock options granted to directors and employees of our subsidiaries and affiliates, we estimate the fair value of each option award on the date of grant using the Black-Scholes option pricing model. The significant assumptions we utilize in applying the Black-Scholes option pricing model are the risk-free interest rate, the expected term, the dividend yield and the expected volatility.

We charged compensation expense related to our stock compensation plans against income before income taxes of $

304,373

and $

314,237

for the three months ended June 30, 2021 and 2020, respectively, with a corresponding income tax benefit of $

63,918

and $

65,990

, respectively. We charged compensation expense related to our stock compensation plans against income before income taxes of $

597,168

and $

644,541

for the six months ended June 30, 2021 and 2020, respectively, with a corresponding income tax benefit of $

125,405

and $

135,354

, respectively. At June 30, 2021, we had $

1.0

million of unrecognized compensation expense related to nonvested share-based compensation granted under our stock compensation plans that we expect to recognize over a weighted average period of approximately

1.6

years.

We received cash from option exercises under all stock compensation plans during the three months ended June 30, 2021 and 2020 of $7.0 million and $2.2 million, respectively. We received cash from option exercises under all stock compensation plans during the six months ended June 30, 2021 and 2020 of $11.4 million and $3.1 million, respectively. We realized actual tax benefits for the tax deductions related to those option exercises of $271,979

and $54,221 for the three months ended June 30, 2021 and 2020, respectively. We realized actual tax benefits for the tax deductions related to those option exercises of $421,135

and $68,878 for the six months ended June 30, 2021 and 2020, respectively.