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Stock-Based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2020
Stock-Based Compensation [Abstract] |
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] | The following table summarizes our restricted stock award activity for the years ended December 31, 2020, 2019 and 2018. The vesting dates for the awards vested in 2020 occurred relatively evenly throughout the year ended December 31, 2020. The fair value of awards vested during 2020, 2019 and 2018 was $2.3 million, $1.8 million and $0.8 million, respectively.
| 2020
| Number of Restricted Stock Awards ( in thousands) |  | Weighted Average Grant Date Fair Value
Unvested at January 1 | 52.1 |  |  | $ | 20.55 |
Granted | 119.9 |  |  | 20.24 |
Vested | (111.8) |  |  | 20.38 |
Forfeited | (0.5) |  |  | 19.32 |
Outstanding (unvested) at end of year | 59.7 |  |  | $ | 20.29 |
| 2019
| Number of Restricted Stock Awards ( in thousands) |  | Weighted Average Grant Date Fair Value
Unvested at January 1 | 26.5 |  |  | $ | 21.31 |
Granted | 114.0 |  |  | 19.88 |
Vested | (87.9) |  |  | 19.93 |
Forfeited | (0.5) |  |  | 17.11 |
Outstanding (unvested) at end of year | 52.1 |  |  | $ | 20.55 |
| 2018
| Number of Restricted Stock Awards (in thousands) |  | Weighted Average Grant Date Fair Value
Unvested at beginning of year | 53.7 |  |  | $ | 21.82 |
Granted | 10.0 |  |  | 18.58 |
Vested | (35.7) |  |  | 21.48 |
Forfeited | (1.5) |  |  | 17.11 |
Outstanding (unvested) at end of year | 26.5 |  |  | $ | 21.31 |

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- Definition Tabular disclosure of share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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