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/disclosureRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt - Summary of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Aug. 31, 2019	Aug. 31, 2017	Jun. 30, 2014
Debt Instrument [Line Items]
Value of debt outstanding	$ 42,257	$ 52,658
4.875% convertible senior notes due 2020
Debt Instrument [Line Items]
Debt instrument, interest rate	4.875%	4.875%			4.875%
Value of debt outstanding	$ 0	$ 1,905	$ 111,100
3.25% convertible senior notes due 2023
Debt Instrument [Line Items]
Debt instrument, interest rate	3.25%	3.25%		3.25%
Value of debt outstanding	$ 42,257	$ 50,753
3.25% convertible senior notes due 2023 \| Carrying Amount
Debt Instrument [Line Items]
Value of debt outstanding	$ 30,700	$ 37,600