Subsequent Events (Details) - $ / shares |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Nov. 07, 2017 |
Aug. 03, 2017 |
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Subsequent Event [Line Items] | ||||||
| Dividends declared per common share (in dollars per share) | $ 0.15 | $ 0.15 | $ 0.14 | $ 0.45 | $ 0.42 | |
| Subsequent event [Member] | ||||||
| Subsequent Event [Line Items] | ||||||
| Dividends declared per common share (in dollars per share) | $ 0.15 | |||||
| Subsequent event [Member] | Preference shares - Series A [Member] | ||||||
| Subsequent Event [Line Items] | ||||||
| Dividends declared per Preference share (in dollars per share) | 0.515625 | |||||
| Subsequent event [Member] | Preference shares - Series C [Member] | ||||||
| Subsequent Event [Line Items] | ||||||
| Dividends declared per Preference share (in dollars per share) | 0.445313 | |||||
| Subsequent event [Member] | Preference shares - Series D [Member] | ||||||
| Subsequent Event [Line Items] | ||||||
| Dividends declared per Preference share (in dollars per share) | $ 0.41875 | |||||