Equipment Lease Obligations - Schedule of Future Minimum Lease Payments for Equipment Lease Obligations (Parenthetical) (Detail) |
Dec. 31, 2017 |
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Minimum | |
Capital Leased Assets [Line Items] | |
Capital leases future minimum payments interest rate | 0.00% |
Maximum | |
Capital Leased Assets [Line Items] | |
Capital leases future minimum payments interest rate | 4.95% |