Supplemental cash flow information (Details) - USD ($) $ in Millions |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
Dec. 31, 2016 |
|
| Schedule of Trading Securities and Other Trading Assets [Line Items] | |||
| Interest | $ 5.8 | $ 5.6 | |
| Income taxes, net | 17.9 | 14.4 | |
| Capital lease arrangements | 14.8 | $ 3.9 | |
| Restricted cash | 70.2 | $ 55.5 | |
| Cash from Short Term Borrowings | |||
| Schedule of Trading Securities and Other Trading Assets [Line Items] | |||
| Restricted cash | 24.0 | 22.3 | |
| Cash Held From Customers | |||
| Schedule of Trading Securities and Other Trading Assets [Line Items] | |||
| Restricted cash | $ 42.9 | $ 33.2 | |