Stock Incentive Plan (Schedule of Nonvested Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) - shares |
12 Months Ended | ||
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Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward] | |||
RSUs granted and unvested at beginning of period: | 4,124,260 | 5,062,661 | 5,216,972 |
Granted | 962,453 | 840,796 | 1,140,048 |
Vested | (1,111,588) | (1,447,522) | (900,254) |
Canceled | (170,789) | (331,675) | (394,105) |
RSUs granted and unvested at end of period: | 3,804,336 | 4,124,260 | 5,062,661 |