Stock Incentive Plan (Schedule of Share-based Compensation, Unearned Compensation Related to RSU's) (Details) - Restricted Stock Units (RSUs) - USD ($) $ in Thousands |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Changes In Unearned Compensation [Roll Forward] | |||
Unearned compensation at beginning of year | $ 128,390 | $ 129,669 | $ 122,910 |
RSUs granted, net of cancellations | 54,270 | 53,583 | 52,204 |
RSUs expensed | 47,108 | (47,329) | (34,408) |
RSUs forfeitures | 3,242 | (7,533) | (11,037) |
Unearned compensation at end of year | $ 132,310 | $ 128,390 | $ 129,669 |