Other Liabilities Accrued and other liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	$ 8,916	$ 7,763
Tax-related
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	238	385
Accrued compensation and related taxes
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	5,471	4,517
Deferred revenue
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	1,308	857
Professional services
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	763	608
Accrued fuel and rig-related charges
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	601	889
Other
Schedule Other Liabilities [Line Items]
Accrued and other liabilities	$ 535	$ 507