Leases - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018
Operating Leased Assets [Line Items]
Operating leases placed in services dates description	SDTS has entered into various leases with Sharyland for all our placed in service regulated assets. The master lease agreements, as amended, expire at various dates from December 31, 2019 through December 31, 2022.
Lease expiration date range, start date	Dec. 31, 2019
Lease expiration date range, end date	Dec. 31, 2022
S/B/C Lease
Operating Leased Assets [Line Items]
Lease terminated date	Dec. 31, 2017
Maximum
Operating Leased Assets [Line Items]
Rate of rent used, Percentage	31.00%
Minimum
Operating Leased Assets [Line Items]
Rate of rent used, Percentage	23.00%