Summary of Significant Accounting Policies - Additional Information 2 (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) Unit $ / shares $ / EquityUnit shares	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) Unit $ / shares $ / EquityUnit shares	Sep. 30, 2015 USD ($)	Dec. 31, 2015 shares
Operations And Summary Of Significant Accounting Policies [Line Items]
Stock-based compensation expense recognized			$ 3,571,000	$ 6,061,000
U.S. Federal
Operations And Summary Of Significant Accounting Policies [Line Items]
Additional valuation allowance on net operating loss carryforwards, net of federal tax benefit	$ 27,600,000		27,600,000
State and Local Jurisdiction
Operations And Summary Of Significant Accounting Policies [Line Items]
Additional valuation allowance on net operating loss carryforwards, net of federal tax benefit	$ 8,300,000		$ 8,300,000
Restricted Stock
Operations And Summary Of Significant Accounting Policies [Line Items]
Number of shares granted | shares			229,644
Restricted stock grant date fair value			$ 1,800,000
Grant date fair value of share units, per unit | $ / shares			$ 5.46
Shares of unvested restricted stock outstanding | shares	354,986		354,986		314,060
Weighted average grant date fair value of stock grants per share | $ / shares	$ 15.27		$ 15.27
Unrecognized compensation cost	$ 3,600,000		$ 3,600,000
Period in which compensation cost expected to be recognized			1 year 6 months
Potential Performance Shares (PSU)
Operations And Summary Of Significant Accounting Policies [Line Items]
Unrecognized compensation cost	$ 1,400,000		$ 1,400,000
Period in which compensation cost expected to be recognized			1 year 6 months
Number of units granted | Unit			60,015
Performance units grant date fair value			$ 400,000
Grant date fair value of share units, per unit | $ / EquityUnit			7.00
Number of performance stock units ("PSUs") outstanding | Unit	134,650		134,650
Weighted average grant date fair value of PSUs per unit | $ / EquityUnit	22.09		22.09
Potential Performance Shares (PSU) | Minimum
Operations And Summary Of Significant Accounting Policies [Line Items]
Common stock, shares, potentially issuable in exchange for Share Units | shares	0		0
Potential Performance Shares (PSU) | Maximum
Operations And Summary Of Significant Accounting Policies [Line Items]
Common stock, shares, potentially issuable in exchange for Share Units | shares	269,300		269,300
Stock Options
Operations And Summary Of Significant Accounting Policies [Line Items]
Unrecognized compensation cost	$ 0		$ 0
Number of Options Outstanding | shares	11,730		11,730
Weighted average exercise price | $ / shares	$ 166.10		$ 166.10
Options, expiration date			Dec. 14, 2016
Number of option, granted | shares			0
Number of option, Exercised | shares			0
General and Administrative Expense
Operations And Summary Of Significant Accounting Policies [Line Items]
Stock-based compensation expense recognized	$ 1,100,000	$ 2,100,000	$ 3,600,000	$ 6,100,000