Shareholders' Equity - Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | 8 Months Ended | |||
|---|---|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Nov. 14, 2016 |
May 02, 2012 |
|
| Equity [Abstract] | ||||||
| Number of shares authorized to be repurchased (in shares) | 500,000.0 | 500,000 | ||||
| Number shares repurchased (in shares) | 0 | 0 | 24,086 | |||
| Payments for repurchase of common stock | $ 0.0 | $ 0.2 | $ 0.2 | |||
| Remaining number of shares authorized to be repurchased (in shares) | 475,914 | 475,914 | 475,914 | |||
| Average price per share of treasury stock acquired and held (in dollars per share) | $ 39.19 | |||||
| Movement in Treasury Stock [Roll Forward] | ||||||
| Beginning balance (in shares) | 744,091 | |||||
| Restricted stock grants (in shares) | (86,000) | |||||
| Forfeitures and other (in shares) | 67,767 | |||||
| Ending balance (in shares) | 725,858 | 725,858 | 725,858 | |||