Sale of Common Units (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Feb. 10, 2017 |
Sep. 30, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2018 |
|
| Sale Of Common Units | |||||
| Maximum aggregate offering price of common limited partners units under an equity distribution agreement | $ 250.0 | ||||
| Units issued and sold (in shares) | 777,262 | 2,391,595 | |||
| Net proceeds from issue and sale of common units | $ 26.0 | $ 65.0 | |||
| Remaining capacity to issue additional common units under an equity distribution agreement | $ 157.0 | ||||
| Common Unitholders Public | |||||
| Sale Of Common Units | |||||
| Sale of units to public (in shares) | 6,900,000 | ||||
| Net proceeds from sale of units | $ 223.0 | ||||