Leases - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) truck	Mar. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Remaining lease terms	99 years
Residual value guarantee	$ 1.5
Lease not yet commenced, amount	$ 3.3
Number of water transfer trucks | truck	20
Lease not yet commenced, term	4 years
Lease expense under operating leases		$ 1.2
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms	20 years