Notes Payable - Future Maturities of CRG Obligation (Detail) - CRG [Member] - Line of Credit [Member] $ in Thousands	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
2018	$ 0
2019	0
2020	20,054
2021	20,054
2022	20,054
Total maturities	60,162
Unamortized discount and loan costs	(11,877)
Total CRG obligation	$ 48,285

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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-Subparagraph (SX 210.7-03(a)(16))
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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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