Leases - Narrative (Details) $ in Millions		3 Months Ended	12 Months Ended
	Feb. 01, 2019 contract	Mar. 31, 2019 USD ($)	Dec. 31, 2018	Jan. 01, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease liability		$ 34.0
Operating lease, right-of-use asset		$ 32.0
Minimum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term		1 month
Maximum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term		7 years 9 months 18 days
Natural Gas Compressors | Midcon Compression, L.L.C.
Lessee, Lease, Description [Line Items]
Lease terms			38 months
Wildhorse Resource Development Corporation
Lessee, Lease, Description [Line Items]
Operating lease liability				$ 40.0
Operating lease, right-of-use asset				38.0
Lease incentive				$ 2.0
Number of leases | contract	2