Summary of Significant Accounting Policies - Additional Information 2 (Detail) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) Unit $ / shares $ / EquityUnit shares	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Unit Product $ / shares $ / EquityUnit shares	Jun. 30, 2017 USD ($)	Dec. 31, 2017 shares
Operations And Summary Of Significant Accounting Policies [Line Items]
Stock-based compensation expense recognized			$ 3,109	$ 2,815
Number of primary products | Product			2
Contract cash settlement max days			25 days
Contract cancellable notice term			30 days
Accounts Receivable related to satisfied performance obligations and unconditional right to consideration	$ 21,500		$ 21,500
Restricted Stock
Operations And Summary Of Significant Accounting Policies [Line Items]
Number of shares granted | shares			445,801
Restricted stock grant date fair value			$ 3,800
Grant date fair value of share units, per share | $ / shares			$ 8.46
Shares of unvested restricted stock outstanding | shares	803,955		803,955		619,867
Weighted average grant date fair value of stock grants per share | $ / shares	$ 8.43		$ 8.43
Unrecognized compensation cost related to unvested restricted stock	$ 5,700		$ 5,700
Period in which compensation cost expected to be recognized			2 years 2 months 12 days
Potential Performance Shares (PSU)
Operations And Summary Of Significant Accounting Policies [Line Items]
Period in which compensation cost expected to be recognized			2 years 3 months 18 days
Number of units granted | Unit			360,801
Performance share units grant date fair value			$ 4,500
Grant date fair value of share units, per unit | $ / EquityUnit			12.52
Number of performance stock units ("PSUs") outstanding | Unit	514,336		514,336
Weighted average grant date fair value of PSUs per unit | $ / EquityUnit	13.83		13.83
Minimum final number of shares of common stock issuable based on performance multiplier | shares			0
Maximum final number of shares of common stock issuable based on performance multiplier | shares			1,028,672
Unrecognized expense, performance share units			$ 6,200
General and Administrative Expense
Operations And Summary Of Significant Accounting Policies [Line Items]
Stock-based compensation expense recognized	$ 1,500	$ 1,500	$ 3,100	$ 2,800