Stock-Based Compensation - Restricted Stock Unit Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Vested (in shares)	(351,938)	(266,091)
Restricted Stock
Shares
Balance at beginning of year (in shares)	977,069	772,016	752,024
Granted (in shares)	789,500	484,450	485,000
Forfeited (in shares)	(209,748)	(13,306)	(70,070)
Vested (in shares)	(351,938)	(266,091)	(394,938)
Balance at end of year (in shares)	1,204,883	977,069	772,016
Weighted Average Grant Date Fair Value
Balance at beginning of year (in dollars per share)	$ 5.36	$ 5.35	$ 6.21
Granted (in dollars per share)	3.33	5.63	4.62
Forfeited (in dollars per share)	4.62	5.27	5.58
Vested (in dollars per share)	5.17	5.84	2.94
Balance at end of year (in dollars per share)	$ 4.21	$ 5.36	$ 5.35