Summary of Significant Accounting Policies - Basis of Consolidation and Presentation - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Accounting Policies [Line Items]
Net loss		$ (14,746,000)	$ (3,561,000)	$ (61,555,000)
Accumulated deficit		$ (359,160,000)	$ (344,414,000)
Common stock, number of shares issued and sold		30,364,501	18,080,944
Proceeds from issuance of common stock in initial public offering, net of issuance costs		$ 73,539,000
Face value of debt			$ 400,000,000
Net proceeds of the Term Facility, IPO and cash	$ 10,900,000
IPO [Member]
Schedule Of Accounting Policies [Line Items]
Common stock, number of shares issued and sold	12,256,577
Proceeds from issuance of common stock in initial public offering, net of issuance costs	$ 67,200,000
Underwriting discounts, commissions and related expenses	$ 6,400,000
Over-Allotment Option [Member]
Schedule Of Accounting Policies [Line Items]
Common stock, number of shares issued and sold	1,423,243
Common Stock [Member] | IPO [Member]
Schedule Of Accounting Policies [Line Items]
Shares issued, price per share	$ 6.00
Senior Secured Term Loan Facility [Member]
Schedule Of Accounting Policies [Line Items]
Face value of debt	$ 365,000,000
Aggregate principal amount outstanding		363,175,000
Senior Notes [Member]
Schedule Of Accounting Policies [Line Items]
Aggregate principal amount outstanding	$ 400,000,000	$ 400,000,000
Notes interest rate		9.75%
Senior Notes Due 2017 [Member]
Schedule Of Accounting Policies [Line Items]
Notes interest rate	9.75%
Revolving Line of Credit [Member]
Schedule Of Accounting Policies [Line Items]
Outstanding borrowing	$ 8,000,000
Borrowing base		$ 48,200,000
Unfunded standby letter of credit outstanding		8,800,000
Available borrowing capacity		39,300,000
Accrued interest		$ 100,000
LMI [Member]
Schedule Of Accounting Policies [Line Items]
Outstanding borrowing	$ 50,000,000