Basis and Summary of Significant Accounting Policies - Calculation of Dilutive Stock Awards (Details) - shares shares in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
| Accounting Policies [Abstract] | ||||
| Weighted Average Shares Outstanding (in shares) | 68,819 | 70,746 | 69,521 | 70,914 |
| Dilutive Effect of Share-Based Awards (in shares) | 1,320 | 1,349 | 1,475 | 1,143 |
| Weighted Average Shares Outstanding Assuming Dilution (in shares) | 70,139 | 72,095 | 70,996 | 72,057 |
| Anti-dilutive securities excluded from the computation of earnings per share assuming dilution (in shares) | 356 | 9 | 345 | 180 |