Stock-Based Compensation - 2018 Performance Stock Units (Details) - Executive officers - Performance-based options - $ / shares |
3 Months Ended | 6 Months Ended |
---|---|---|
Mar. 31, 2018 |
Jun. 30, 2018 |
|
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Number of stock units granted (shares) | 167,000 | 167,000 |
Minimum | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Award vesting percentage | 0.00% | |
Weighted average fair value per stock units granted (usd per share) | $ 10.09 | $ 10.09 |
Maximum | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Award vesting percentage | 200.00% |