Weighted-Average Assumptions used to Estimate Fair Value of Stock Options and Restricted Stock Awards using Black-Scholes Valuation Model (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected volatility			100.78%	102.40%
Expected dividends			2.05%	5.07%
Expected term (in years)			6 years 7 months 6 days	8 years 2 months 12 days
Risk-free interest rate			1.06%	1.66%