Quarterly report pursuant to Section 13 or 15(d)

Leases - Additional Information (Detail)

v3.7.0.1
Leases - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Leases [Line Items]      
Pump equipment $ 14.0   $ 13.9
Accumulated depreciation related to leased assets 4.4   $ 3.9
Operating lease rental expenses $ 0.2 $ 0.2  
Capital Leases [Member]      
Leases [Line Items]      
Weighted average interest rate under capital leases 4.60%