Subsequent Events - Additional Information (Detail)
$ / shares in Units, $ in Millions |
|
|
|
3 Months Ended |
|
Nov. 04, 2016
$ / shares
|
Oct. 17, 2016
USD ($)
MW
|
Sep. 21, 2016
MW
|
Sep. 30, 2016
$ / shares
|
Jun. 30, 2016
$ / shares
|
Mar. 31, 2016
$ / shares
|
| Subsequent Event [Line Items] |
|
|
|
|
|
|
| Dividend declaration Date |
|
|
|
Aug. 03, 2016
|
May 04, 2016
|
Feb. 24, 2016
|
| Dividend payment Date |
|
|
|
Oct. 31, 2016
|
Jul. 29, 2016
|
Apr. 29, 2016
|
| Dividend record Date |
|
|
|
Sep. 30, 2016
|
Jun. 30, 2016
|
Mar. 31, 2016
|
| Dividends payable Per Share (in dollars per share) |
|
|
|
$ 0.4000
|
$ 0.3900
|
$ 0.3810
|
| Subsequent Event [Member] |
|
|
|
|
|
|
| Subsequent Event [Line Items] |
|
|
|
|
|
|
| Dividends payable Per Share (in dollars per share) |
$ 0.4080
|
|
|
|
|
|
| Dividends annualized (in dollars per share) |
$ 1.632
|
|
|
|
|
|
| Increase in dividends payable percentage |
2.00%
|
|
|
|
|
|
| Payments to Acquire Equity Method Investments | $ |
|
$ 133.0
|
|
|
|
|
| Noncash or Part Noncash Acquisition, Debt Assumed | $ |
|
$ 197.1
|
|
|
|
|
| Armow [Member] |
|
|
|
|
|
|
| Subsequent Event [Line Items] |
|
|
|
|
|
|
| Generating capacity | MW |
|
|
179
|
|
|
|
| Armow [Member] | Subsequent Event [Member] |
|
|
|
|
|
|
| Subsequent Event [Line Items] |
|
|
|
|
|
|
| Ownership Percentage |
|
50.00%
|
|
|
|
|
| Generating capacity | MW |
|
179
|
|
|
|
|
| Armow GP [Member] | Subsequent Event [Member] |
|
|
|
|
|
|
| Subsequent Event [Line Items] |
|
|
|
|
|
|
| Ownership Percentage |
|
100.00%
|
|
|
|
|