Stock-Based Compensation - Assumptions Used Estimate Fair Value of Employee Stock Purchase Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended				12 Months Ended			6 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2014 Scenario, Forecast [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares purchased for offering period	19,490	18,594	8,052	44,666
Fair value per share	$ 0.44	$ 0.65	$ 0.93	$ 0.69				$ 0.30
Assumptions
Risk-free interest rate (average)	0.11%	0.14%	0.14%	0.50%	0.60%	0.50%	0.20%	0.40%
Expected dividend yield
Weighted average expected life (years)	6 months	6 months	6 months	6 months	4 years	4 years	1 year	6 months
Volatility (average)	45.00%	74.00%	78.00%	105.00%	68.10%	80.00%	73.00%	44.00%