Commitments and Contingencies - Future Minimum Payments Under All Leases and Loan Payable (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Less current maturities, bond payable and loan payable		$ 125,000us-gaap_LongTermDebtCurrent
Less current maturities, Capital Leases	20,191us-gaap_CapitalLeaseObligationsCurrent	21,316us-gaap_CapitalLeaseObligationsCurrent
CIRM [Member]
Loss Contingencies [Line Items]
2015	679,166
2017	0
2018	0
2019	0
Thereafter	0
Total minimum loan payments	679,166
Less amounts representing interest	0
Principal amounts of bond payable and loan payable	679,166
Principal amounts of bond payable and loan payable	679,166
Less current maturities, bond payable and loan payable	679,166
Silicon Valley Bank [Member]
Loss Contingencies [Line Items]
2015	4,322,035
2016	1,440,678
2017	0
2018	0
2019	0
Thereafter	0
Total minimum loan payments	5,762,713
Less amounts representing interest	240,899
Principal amounts of bond payable and loan payable	5,521,814
Principal amounts of bond payable and loan payable	5,521,814
Less current maturities, bond payable and loan payable	4,099,319
Bond payable and loan payable, less current maturities	1,422,495
Operating Leases [Member]
Loss Contingencies [Line Items]
Operating Leases, 2015	1,981,461
Operating Leases, 2016	1,968,459
Operating Leases, 2017	2,014,706
Operating Leases, 2018	2,061,260
Operating Leases, 2019	2,108,130
Operating Leases, Thereafter	6,088,780
Total minimum lease payments, Operating Leases	16,222,796
Capital Leases [Member]
Loss Contingencies [Line Items]
Capital Leases, 2015	21,591
Capital Leases, 2016	9,454
Capital Leases, 2017	0
Capital Leases, 2018	0
Capital Leases, 2019	0
Capital Leases, Thereafter	0
Total minimum lease payments, Capital Leases	31,045
Less amounts representing interest, Capital Leases	1,624
Principal amounts of bond payable, loan payable and capital lease obligations, Capital Leases	29,421
Principal amounts of bond payable, loan payable and capital lease obligations, Capital Leases	29,421
Less current maturities, Capital Leases	20,191
Capital Leases, Less current maturities	$ 9,230

Bonds payable interest expense long term debt.

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