(Unaudited, in thousands)
Three Months Ended June 30, | Six Months Ended June 30, | |||||||||||||||
2021 | 2020 | 2021 | 2020 | |||||||||||||
Total operating income | $ | 60,628 | $ | 27,955 | $ | 106,714 | $ | 58,941 | ||||||||
Adjustments to reconcile total operating income to non-GAAP total operating income: | ||||||||||||||||
Stock-based compensation expense | 32,126 | 21,044 | 60,710 | 39,606 | ||||||||||||
Deferred compensation plan expense | 2,152 | 4,032 | 3,272 | 377 | ||||||||||||
Non-GAAP operating income | $ | 94,906 | $ | 53,031 | $ | 170,696 | $ | 98,924 |