Supplementary Data Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
Feb. 10, 2017 |
Feb. 12, 2016 |
|
| Disclosure of Repurchase Agreements [Abstract] | ||||
| Stock repurchase program, authorized amount | $ 300.0 | $ 300.0 | ||
| Number of shares repurchased | 2.3 | 2.5 | ||
| Aggregate cost, including fees | $ 55.0 | $ 53.7 | ||
| Average price per share, including fees | $ 23.85 | $ 21.67 | ||
| Stock repurchase program, remaining authorized repurchase amount, excluding fees | $ 400.4 | |||