Fair Value of Financial Instruments - Quantitative Information About Significant Unobservable Inputs (Additional Information) (Detail) - Equity warrant assets	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Other assets
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average contractual remaining term	5 years 9 months 14 days
Estimated remaining life	2 years 7 months 6 days
Level 3 | Other assets
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Sales restrictions discount	18.50%	17.80%
Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Sales restrictions discount	10.00%
Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Sales restrictions discount	20.00%