Subsequent events (Details) - Subsequent Events [Member] $ / shares in Units, $ in Millions |
Aug. 02, 2019
USD ($)
MW
$ / shares
|
Jul. 30, 2019
USD ($)
|
|---|---|---|
| Revolving credit facility [Abstract] | ||
| Additional increase | $ 125 | |
| Maximum borrowing capacity | $ 425 | |
| Dividends approved [Abstract] | ||
| Dividend approved (in dollars per share) | $ / shares | $ 0.40 | |
| Dividend approved expected date to be paid | Sep. 13, 2019 | |
| ASI Operations LLC [Member] | ||
| Acquistions [Abstract] | ||
| Purchase price | $ 6 | |
| ASI Operations LLC [Member] | Bottom of range [member] | ||
| Acquistions [Abstract] | ||
| Cost reduction | 5 | |
| ASI Operations LLC [Member] | Top of range [member] | ||
| Acquistions [Abstract] | ||
| Cost reduction | $ 6 | |
| Monterrey [Member] | ||
| Acquistions [Abstract] | ||
| Ownership percentage acquired | 30.00% | |
| Power capacity | MW | 142 | |
| Installed capacity | MW | 130 | |
| Battery capacity | MW | 12 | |
| Total equity investment | $ 42 |