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 6 Months Ended 12 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Leases [Line Items]          
Pump equipment     $ 14.0   $ 13.9
Accumulated depreciation related to leased assets $ 4.9   4.9   $ 3.9
Operating lease rental expenses $ 0.3 $ 0.3 $ 0.5 $ 0.5  
Capital Leases [Member]          
Leases [Line Items]          
Weighted average interest rate under capital leases 4.30%   4.30%