|
Segment information - Assets, Long Lived Assets, Revnues, Net Assets by Geographic Area (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2015
|
Dec. 31, 2014
|
|---|---|---|
| Segment Reporting Information [Line Items] | ||
| Total assets | $ 2,052.0 | $ 2,192.2 |